diff --git a/mypy/checker.py b/mypy/checker.py
index 431d2d38aabe..4f2de7f894b9 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -1566,12 +1566,14 @@ def check_lvalue(self, lvalue: Lvalue) -> Tuple[Type, IndexExpr, Var]:
         elif isinstance(lvalue, IndexExpr):
             index_lvalue = lvalue
         elif isinstance(lvalue, MemberExpr):
-            lvalue_type = self.expr_checker.analyze_ordinary_member_access(lvalue,
-                                                                 True)
+            lvalue_type = self.expr_checker.analyze_ordinary_member_access(lvalue, True)
             self.store_type(lvalue, lvalue_type)
         elif isinstance(lvalue, NameExpr):
             lvalue_type = self.expr_checker.analyze_ref_expr(lvalue, lvalue=True)
-            self.store_type(lvalue, lvalue_type)
+            if lvalue.name == '_':
+                lvalue_type = AnyType()
+            else:
+                self.store_type(lvalue, lvalue_type)
         elif isinstance(lvalue, TupleExpr) or isinstance(lvalue, ListExpr):
             types = [self.check_lvalue(sub_expr)[0] for sub_expr in lvalue.items]
             lvalue_type = TupleType(types, self.named_type('builtins.tuple'))
diff --git a/mypy/semanal.py b/mypy/semanal.py
index 8f285c135242..afe395ff5cfa 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -3294,7 +3294,8 @@ def name_not_defined(self, name: str, ctx: Context) -> None:
         self.fail(message, ctx)
 
     def name_already_defined(self, name: str, ctx: Context) -> None:
-        self.fail("Name '{}' already defined".format(name), ctx)
+        if name != '_':
+            self.fail("Name '{}' already defined".format(name), ctx)
 
     def fail(self, msg: str, ctx: Context, serious: bool = False, *,
              blocker: bool = False) -> None:
diff --git a/test-data/unit/check-basic.test b/test-data/unit/check-basic.test
index 05fa1a954cc2..9c7b63dfe80f 100644
--- a/test-data/unit/check-basic.test
+++ b/test-data/unit/check-basic.test
@@ -261,6 +261,26 @@ main:3: error: Incompatible types in assignment (expression has type "B", variab
 main:7: error: Incompatible types in assignment (expression has type "A", variable has type "B")
 main:9: error: Incompatible types in assignment (expression has type "B", variable has type "A")
 
+[case testUnderscoreVariableIsFresh]
+from typing import Tuple
+_ = 1
+_ = ""
+_ = ""  # type: int
+(_, _) = ("", 1.0 + "")  # E: Unsupported left operand type for + ("float")
+(_, _) = (1.0, "")
+for (_, _) in ((1, "a"), (2, "b")): pass
+(None for (_, _) in ((1, "a"), (2, "b")))
+
+class A:
+    def __enter__(self) -> Tuple[int, str]: ...
+    def __exit__(self, *_) -> None: ...
+
+with A() as (_, _): pass
+
+def f(_: int) -> None:
+    _ = ""
+    _, _ = (1.0, b"")
+
 [case testGlobalDefinedInBlockWithType]
 
 class A: pass