diff --git a/python/src/com/jetbrains/python/documentation/PyTypeModelBuilder.java b/python/src/com/jetbrains/python/documentation/PyTypeModelBuilder.java
index 4dd9eddc35aa..e40bb820cf14 100644
--- a/python/src/com/jetbrains/python/documentation/PyTypeModelBuilder.java
+++ b/python/src/com/jetbrains/python/documentation/PyTypeModelBuilder.java
@@ -266,9 +266,11 @@ public class PyTypeModelBuilder {
     public void unknown(UnknownType type) {
       final TypeModel nested = type.type;
       if (nested != null) {
+        add("Union[");
         nested.accept(this);
+        add(", " + PyNames.UNKNOWN_TYPE);
+        add("]");
       }
-      add(" | " + PyNames.UNKNOWN_TYPE);
     }
   }
 
@@ -310,7 +312,9 @@ public class PyTypeModelBuilder {
         add("...");
         return;
       }
-      processList(oneOf.oneOfTypes, " | ");
+      add("Union[");
+      processList(oneOf.oneOfTypes, ", ");
+      add("]");
       myDepth--;
     }
 
diff --git a/python/testData/inspections/PyTypeCheckerInspection/BuiltinNumeric.py b/python/testData/inspections/PyTypeCheckerInspection/BuiltinNumeric.py
index b44e59bdc4bc..8bfe76196b43 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/BuiltinNumeric.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/BuiltinNumeric.py
@@ -7,4 +7,4 @@ def test():
     divmod(False, False)
     divmod(<warning descr="Expected type 'Number', got 'str' instead">'foo'</warning>, <warning descr="Expected type 'Number', got 'unicode' instead">u'bar'</warning>)
     pow(False, True)
-    round(False, <warning descr="Expected type 'Integral | None', got 'str' instead">'foo'</warning>)
+    round(False, <warning descr="Expected type 'Union[Integral, None]', got 'str' instead">'foo'</warning>)
diff --git a/python/testData/inspections/PyTypeCheckerInspection/BuiltinsPy3.py b/python/testData/inspections/PyTypeCheckerInspection/BuiltinsPy3.py
index 4156d651dae3..67f40dd5e5d4 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/BuiltinsPy3.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/BuiltinsPy3.py
@@ -13,4 +13,4 @@ def test_numerics():
     divmod(False, False)
     divmod(<warning descr="Expected type 'Number', got 'bytes' instead">b'foo'</warning>, <warning descr="Expected type 'Number', got 'str' instead">'bar'</warning>)
     pow(False, True)
-    round(False, <warning descr="Expected type 'Integral | None', got 'str' instead">'foo'</warning>)
+    round(False, <warning descr="Expected type 'Union[Integral, None]', got 'str' instead">'foo'</warning>)
diff --git a/python/testData/inspections/PyTypeCheckerInspection/DictLiterals.py b/python/testData/inspections/PyTypeCheckerInspection/DictLiterals.py
index eb27a50a033f..d229a0384150 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/DictLiterals.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/DictLiterals.py
@@ -3,6 +3,6 @@ def test():
     for v in xs.values():
         print(v + <warning descr="Expected type 'Number', got 'None' instead">None</warning>)
     for k in xs.keys():
-        print(k + <warning descr="Expected type 'str | unicode', got 'None' instead">None</warning>)
+        print(k + <warning descr="Expected type 'Union[str, unicode]', got 'None' instead">None</warning>)
     for k in xs:
-        print(k + <warning descr="Expected type 'str | unicode', got 'None' instead">None</warning>)
+        print(k + <warning descr="Expected type 'Union[str, unicode]', got 'None' instead">None</warning>)
diff --git a/python/testData/inspections/PyTypeCheckerInspection/Generator.py b/python/testData/inspections/PyTypeCheckerInspection/Generator.py
index 7523940a8593..95481a651b42 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/Generator.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/Generator.py
@@ -89,9 +89,9 @@ def test():
         f_8(<warning descr="Expected type 'Container', got '__generator[str]' instead">gen(11)</warning>),
         f_9(gen(11)),
         f_10(gen(11)),
-        f_11(<warning descr="Expected type 'list[str | unicode]', got '__generator[str]' instead">gen(11)</warning>),
-        f_12(<warning descr="Expected type 'Sequence[str | unicode]', got '__generator[str]' instead">gen(11)</warning>),
-        f_13(<warning descr="Expected type 'Container[str | unicode]', got '__generator[str]' instead">gen(11)</warning>),
+        f_11(<warning descr="Expected type 'list[Union[str, unicode]]', got '__generator[str]' instead">gen(11)</warning>),
+        f_12(<warning descr="Expected type 'Sequence[Union[str, unicode]]', got '__generator[str]' instead">gen(11)</warning>),
+        f_13(<warning descr="Expected type 'Container[Union[str, unicode]]', got '__generator[str]' instead">gen(11)</warning>),
         f_14(gen(11)),
         f_15(gen(11)),
         f_15('foo'.split('o')),
diff --git a/python/testData/inspections/PyTypeCheckerInspection/ListTuple.py b/python/testData/inspections/PyTypeCheckerInspection/ListTuple.py
index 2dfd05166f70..e47e9363ce5a 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/ListTuple.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/ListTuple.py
@@ -7,5 +7,5 @@ def f(spam, eggs):
 
 
 def test():
-    f(<warning descr="Expected type 'list[str | unicode]', got 'list[int]' instead">[1, 2, 3]</warning>,
+    f(<warning descr="Expected type 'list[Union[str, unicode]]', got 'list[int]' instead">[1, 2, 3]</warning>,
       (<warning descr="Expected type '(bool, int, unicode)', got '(bool, int, str)' instead">False, 2, ''</warning>))
diff --git a/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py b/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py
index a27266914eed..14563237d69e 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py
@@ -2,4 +2,4 @@ def test():
     xs = map(lambda x: x + 1, [1, 2, 3])
     print('foo' + xs[0])  # Can be a str since map returns list[V] | str | unicode
     ys = map(tuple, iter([1, 2, 3]))
-    print(1 + <warning descr="Expected type 'Number', got 'tuple | str | unicode' instead">ys[0]</warning>, 'bar' + ys[1])
+    print(1 + <warning descr="Expected type 'Number', got 'Union[tuple, str, unicode]' instead">ys[0]</warning>, 'bar' + ys[1])
diff --git a/python/testData/inspections/PyTypeCheckerInspection/PropertyAndFactoryFunction.py b/python/testData/inspections/PyTypeCheckerInspection/PropertyAndFactoryFunction.py
index 8cf0bfcce4a9..deca51ac5459 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/PropertyAndFactoryFunction.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/PropertyAndFactoryFunction.py
@@ -7,4 +7,4 @@ def f():
     return C()
 
 def test():
-    f().foo + <warning descr="Expected type 'str | unicode', got 'int' instead">1</warning>
+    f().foo + <warning descr="Expected type 'Union[str, unicode]', got 'int' instead">1</warning>
diff --git a/python/testData/inspections/PyTypeCheckerInspection/SecondFormIter.py b/python/testData/inspections/PyTypeCheckerInspection/SecondFormIter.py
index bf0a0e80c6a2..4d2cbf6a7a6b 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/SecondFormIter.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/SecondFormIter.py
@@ -7,7 +7,7 @@ def test_second_form():
 
 
 def test_second_form_fail():
-    for chunk in iter(<weak_warning descr="Expected type 'Iterable | () -> object' (matched generic type 'Iterable[T] | () -> object'), got 'int' instead">10</weak_warning>, ''):
+    for chunk in iter(<weak_warning descr="Expected type 'Union[Iterable, () -> object]' (matched generic type 'Union[Iterable[T], () -> object]'), got 'int' instead">10</weak_warning>, ''):
         pass
 
 
diff --git a/python/testData/inspections/PyTypeCheckerInspection/StringInteger.py b/python/testData/inspections/PyTypeCheckerInspection/StringInteger.py
index caad34d184ed..6f1e0e418d58 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/StringInteger.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/StringInteger.py
@@ -1,8 +1,8 @@
 def test():
     print('foo' + 'bar')
     print(2 + 3)
-    print('foo' + <warning descr="Expected type 'str | unicode', got 'int' instead">3</warning>)
+    print('foo' + <warning descr="Expected type 'Union[str, unicode]', got 'int' instead">3</warning>)
     print(3 + <warning descr="Expected type 'Number', got 'str' instead">'foo'</warning>)
     print('foo' + 'bar' * 3)
     print('foo' + 3 * 'bar')
-    print('foo' + <warning descr="Expected type 'str | unicode', got 'int' instead">2 * 3</warning>)
+    print('foo' + <warning descr="Expected type 'Union[str, unicode]', got 'int' instead">2 * 3</warning>)
diff --git a/python/testData/inspections/PyTypeCheckerInspection/StringStartsWith.py b/python/testData/inspections/PyTypeCheckerInspection/StringStartsWith.py
index dae1ba9955e0..7bb15093b687 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/StringStartsWith.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/StringStartsWith.py
@@ -1,7 +1,7 @@
 'foo'.startswith('bar')
 'foo'.startswith(('bar', 'baz'))
-'foo'.startswith(<warning descr="Expected type 'str | unicode | tuple', got 'int' instead">2</warning>)
+'foo'.startswith(<warning descr="Expected type 'Union[str, unicode, tuple]', got 'int' instead">2</warning>)
 
 u'foo'.startswith(u'bar')
 u'foo'.startswith((u'bar', u'baz'))
-u'foo'.startswith(<warning descr="Expected type 'str | unicode | tuple', got 'int' instead">2</warning>)
+u'foo'.startswith(<warning descr="Expected type 'Union[str, unicode, tuple]', got 'int' instead">2</warning>)
diff --git a/python/testData/inspections/PyTypeCheckerInspection/UnionReturnTypes.py b/python/testData/inspections/PyTypeCheckerInspection/UnionReturnTypes.py
index 5c2d00d3b53c..30e2ab7ddda1 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/UnionReturnTypes.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/UnionReturnTypes.py
@@ -17,7 +17,7 @@ def test(c):
         """
     x1 = f1(c)
     f2(x1)  # Weaker union types
-    f3(<warning descr="Expected type 'int', got 'list | str | None' instead">x1</warning>)
+    f3(<warning descr="Expected type 'int', got 'Union[list, str, None]' instead">x1</warning>)
 
     f2(<warning descr="Expected type 'str', got 'int' instead">x1.count('')</warning>)
     f3(x1.count(''))
diff --git a/python/testData/inspections/PyTypeCheckerInspection/WithOpenBinaryPy3.py b/python/testData/inspections/PyTypeCheckerInspection/WithOpenBinaryPy3.py
index 9198f3f6ea89..7527db0f95f3 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/WithOpenBinaryPy3.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/WithOpenBinaryPy3.py
@@ -2,4 +2,4 @@ with open('foo', 'wb') as fd:
     fd.write(b'bar')
 
 with open('foo', 'wb') as fd:
-    fd.write(<warning descr="Expected type 'bytes | bytearray', got 'str' instead">'bar'</warning>)
+    fd.write(<warning descr="Expected type 'Union[bytes, bytearray]', got 'str' instead">'bar'</warning>)
diff --git a/python/testData/quickdoc/HoverOverControlFlowUnion.html b/python/testData/quickdoc/HoverOverControlFlowUnion.html
index 5b9ce6b5ca02..1863ee9781d8 100644
--- a/python/testData/quickdoc/HoverOverControlFlowUnion.html
+++ b/python/testData/quickdoc/HoverOverControlFlowUnion.html
@@ -1,2 +1,2 @@
 variable "x"
-Inferred type: str | int
+Inferred type: Union[str, int]
diff --git a/python/testData/quickdoc/Variable.html b/python/testData/quickdoc/Variable.html
index eac55f8d9c13..68812118dd74 100644
--- a/python/testData/quickdoc/Variable.html
+++ b/python/testData/quickdoc/Variable.html
@@ -1 +1 @@
-<html><body><small>Assigned to <code>y</code><br></small><code><br>Inferred&nbsp;type:&nbsp;<a href="psi_element://#typename#int">int</a>&nbsp;|&nbsp;<a href="psi_element://#typename#str">str</a></code></body></html>
+<html><body><small>Assigned to <code>y</code><br></small><code><br>Inferred&nbsp;type:&nbsp;Union[<a href="psi_element://#typename#int">int</a>,&nbsp;<a href="psi_element://#typename#str">str</a>]</code></body></html>
diff --git a/python/testSrc/com/jetbrains/python/PyTypeTest.java b/python/testSrc/com/jetbrains/python/PyTypeTest.java
index 3f1bb071fe94..a382972245a9 100644
--- a/python/testSrc/com/jetbrains/python/PyTypeTest.java
+++ b/python/testSrc/com/jetbrains/python/PyTypeTest.java
@@ -42,9 +42,9 @@ public class PyTypeTest extends PyTestCase {
   public void testBinaryExprType() {
     doTest("int",
            "expr = 1 + 2");
-    doTest("str | unicode",
+    doTest("Union[str, unicode]",
            "expr = '1' + '2'");
-    doTest("str | unicode",
+    doTest("Union[str, unicode]",
            "expr = '%s' % ('a')");
     doTest("list[int]",
            "expr = [1] + [2]");
@@ -238,7 +238,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testUnknownTypeInUnion() {
-    doTest("int | Any",
+    doTest("Union[int, Any]",
            "def f(c, x):\n" +
            "    if c:\n" +
            "        return 1\n" +
@@ -361,7 +361,7 @@ public class PyTypeTest extends PyTestCase {
   public void testYieldFromType() {
     PythonLanguageLevelPusher.setForcedLanguageLevel(myFixture.getProject(), LanguageLevel.PYTHON33);
     try {
-      doTest("str | int | float",
+      doTest("Union[str, int, float]",
              "def subgen():\n" +
              "    for i in [1, 2, 3]:\n" +
              "        yield i\n" +
@@ -570,7 +570,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testLogicalAndExpression() {
-    doTest("str | int",
+    doTest("Union[str, int]",
            "expr = 'foo' and 2");
   }
 
@@ -596,11 +596,11 @@ public class PyTypeTest extends PyTestCase {
                         "    foo(3)\n" +
                         "    foo('bar')\n";
     final PyExpression expr = parseExpr(text);
-    doTest("int | str | Any", expr, TypeEvalContext.codeCompletion(expr.getProject(), expr.getContainingFile()));
+    doTest("Union[Union[int, str], Any]", expr, TypeEvalContext.codeCompletion(expr.getProject(), expr.getContainingFile()));
   }
 
   public void testUpperBoundGeneric() {
-    doTest("int | str",
+    doTest("Union[int, str]",
            "def foo(x):\n" +
            "    '''\n" +
            "    :type x: T <= int or str\n" +
@@ -622,7 +622,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testFunctionTypeAsUnificationArgument() {
-    doTest("list[int] | str | unicode",
+    doTest("Union[list[int], str, unicode]",
            "def map2(f, xs):\n" +
            "    '''\n" +
            "    :type f: (T) -> V | None\n" +
@@ -635,7 +635,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testFunctionTypeAsUnificationArgumentWithSubscription() {
-    doTest("int | str | unicode",
+    doTest("Union[int, str, unicode]",
            "def map2(f, xs):\n" +
            "    '''\n" +
            "    :type f: (T) -> V | None\n" +
@@ -764,7 +764,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testNoResolveToFunctionsInTypes() {
-    doTest("C | Any",
+    doTest("Union[C, Any]",
            "class C(object):\n" +
            "    def bar(self):\n" +
            "        pass\n" +
@@ -777,7 +777,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testIsInstanceExpressionResolvedToTuple() {
-    doTest("str | unicode",
+    doTest("Union[str, unicode]",
            "string_types = str, unicode\n" +
            "\n" +
            "def f(x):\n" +
@@ -786,7 +786,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testIsInstanceInConditionalExpression() {
-    doTest("str | int",
+    doTest("Union[str, int]",
            "def f(x):\n" +
            "    expr = x if isinstance(x, str) else 10\n");
   }
@@ -837,7 +837,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testTupleIterationType() {
-    doTest("int | str",
+    doTest("Union[int, str]",
            "xs = (1, 'a')\n" +
            "for expr in xs:\n" +
            "    pass\n");
@@ -900,7 +900,7 @@ public class PyTypeTest extends PyTestCase {
   }
 
   public void testUnionTypeAttributeOfDifferentTypes() {
-    doTest("list | int",
+    doTest("Union[list, int]",
            "class Foo:\n" +
            "    x = []\n" +
            "\n" +
@@ -914,7 +914,7 @@ public class PyTypeTest extends PyTestCase {
 
   // PY-11364
   public void testUnionTypeAttributeCallOfDifferentTypes() {
-    doTest("C1 | C2",
+    doTest("Union[C1, C2]",
            "class C1:\n" +
            "    def foo(self):\n" +
            "        return self\n" +
@@ -934,7 +934,7 @@ public class PyTypeTest extends PyTestCase {
 
   // PY-12862
   public void testUnionTypeAttributeSubscriptionOfDifferentTypes() {
-    doTest("C1 | C2",
+    doTest("Union[C1, C2]",
            "class C1:\n" +
            "    def __getitem__(self, item):\n" +
            "        return self\n" +
@@ -955,7 +955,7 @@ public class PyTypeTest extends PyTestCase {
 
   // PY-11541
   public void testIsInstanceBaseStringCheck() {
-    doTest("str | unicode",
+    doTest("Union[str, unicode]",
            "def f(x):\n" +
            "    if isinstance(x, basestring):\n" +
            "        expr = x\n");
diff --git a/python/testSrc/com/jetbrains/python/PyTypingTest.java b/python/testSrc/com/jetbrains/python/PyTypingTest.java
index 3d4c95085274..a1114b4e5e98 100644
--- a/python/testSrc/com/jetbrains/python/PyTypingTest.java
+++ b/python/testSrc/com/jetbrains/python/PyTypingTest.java
@@ -84,7 +84,7 @@ public class PyTypingTest extends PyTestCase {
   }
 
   public void testUnionType() {
-    doTest("int | str",
+    doTest("Union[int, str]",
            "from typing import Union\n" +
            "\n" +
            "def f(expr: Union[int, str]):\n" +
@@ -214,7 +214,7 @@ public class PyTypingTest extends PyTestCase {
   }
 
   public void testAnyStrForUnknown() {
-    doTest("bytes | str",
+    doTest("Union[bytes, str]",
            "from typing import AnyStr\n" +
            "\n" +
            "def foo(x: AnyStr) -> AnyStr:\n" +