diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py
index 14650b1b5242..1cd40d474966 100644
--- a/mypy/checkexpr.py
+++ b/mypy/checkexpr.py
@@ -6012,6 +6012,9 @@ def visit_dictionary_comprehension(self, e: DictionaryComprehension) -> Type:
                 name="<dictionary-comprehension>",
                 variables=[ktdef, vtdef],
             )
+            if e.key is None:
+                self.chk.fail("PEP 798 is not supported yet", e)
+                return AnyType(TypeOfAny.from_error)
             return self.check_call(
                 constructor, [e.key, e.value], [nodes.ARG_POS, nodes.ARG_POS], e
             )[0]
diff --git a/mypy/nativeparse.py b/mypy/nativeparse.py
index cd74f81b1d91..093f50f59e31 100644
--- a/mypy/nativeparse.py
+++ b/mypy/nativeparse.py
@@ -295,7 +295,7 @@ def parse_to_binary_ast(
         platform=options.platform,
         always_true=options.always_true,
         always_false=options.always_false,
-        cache_version=3,
+        cache_version=4,
     )
     return (
         ast_bytes,
@@ -1564,7 +1564,11 @@ def read_expression(state: State, data: ReadBuffer) -> Expression:
         expect_end_tag(data)
         return expr
     elif tag == nodes.DICT_COMPREHENSION:
-        key = read_expression(state, data)
+        has_key = read_bool(data)
+        if has_key:
+            key = read_expression(state, data)
+        else:
+            key = None
         value = read_expression(state, data)
         n_generators = read_int(data)
         indices = [read_expression(state, data) for _ in range(n_generators)]
@@ -1573,6 +1577,9 @@ def read_expression(state: State, data: ReadBuffer) -> Expression:
         is_async = [read_bool(data) for _ in range(n_generators)]
         expr = DictionaryComprehension(key, value, indices, sequences, condlists, is_async)
         read_loc(data, expr)
+        if key is None:
+            # TODO: add similar check to other kinds of comprehensions.
+            state.check_min_version("Unpacking in comprehensions", (3, 15), expr.line, expr.column)
         expect_end_tag(data)
         return expr
     elif tag == nodes.SET_COMPREHENSION:
diff --git a/mypy/nodes.py b/mypy/nodes.py
index cbeda29ec74a..53efc1fbc86b 100644
--- a/mypy/nodes.py
+++ b/mypy/nodes.py
@@ -3066,7 +3066,7 @@ class DictionaryComprehension(Expression):
 
     __match_args__ = ("key", "value", "indices", "sequences", "condlists")
 
-    key: Expression
+    key: Expression | None
     value: Expression
     sequences: list[Expression]
     condlists: list[list[Expression]]
@@ -3075,7 +3075,7 @@ class DictionaryComprehension(Expression):
 
     def __init__(
         self,
-        key: Expression,
+        key: Expression | None,
         value: Expression,
         indices: list[Lvalue],
         sequences: list[Expression],
diff --git a/mypy/semanal.py b/mypy/semanal.py
index cd1b0a738974..bceade1b1ac1 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -6461,7 +6461,8 @@ def visit_dictionary_comprehension(self, expr: DictionaryComprehension) -> None:
 
         with self.enter(expr):
             self.analyze_comp_for(expr)
-            expr.key.accept(self)
+            if expr.key is not None:
+                expr.key.accept(self)
             expr.value.accept(self)
         self.analyze_comp_for_2(expr)
 
diff --git a/mypy/traverser.py b/mypy/traverser.py
index 6fdb54298f85..224d3b3460eb 100644
--- a/mypy/traverser.py
+++ b/mypy/traverser.py
@@ -363,7 +363,8 @@ def visit_dictionary_comprehension(self, o: DictionaryComprehension, /) -> None:
             index.accept(self)
             for cond in conditions:
                 cond.accept(self)
-        o.key.accept(self)
+        if o.key is not None:
+            o.key.accept(self)
         o.value.accept(self)
 
     def visit_list_comprehension(self, o: ListComprehension, /) -> None:
diff --git a/mypy/treetransform.py b/mypy/treetransform.py
index 25092de66a14..c5e1ad44ea4c 100644
--- a/mypy/treetransform.py
+++ b/mypy/treetransform.py
@@ -628,7 +628,7 @@ def visit_dictionary_comprehension(
         self, node: DictionaryComprehension
     ) -> DictionaryComprehension:
         return DictionaryComprehension(
-            self.expr(node.key),
+            self.optional_expr(node.key),
             self.expr(node.value),
             [self.expr(index) for index in node.indices],
             [self.expr(s) for s in node.sequences],
diff --git a/mypyc/irbuild/expression.py b/mypyc/irbuild/expression.py
index 91e1e55d8da2..6681fcd0825a 100644
--- a/mypyc/irbuild/expression.py
+++ b/mypyc/irbuild/expression.py
@@ -1419,7 +1419,11 @@ def _dict_comp_body(builder: IRBuilder, o: DictionaryComprehension) -> Value:
     loop_params = list(zip(o.indices, o.sequences, o.condlists, o.is_async))
 
     def gen_inner_stmts() -> None:
-        k = builder.accept(o.key)
+        if o.key is not None:
+            k = builder.accept(o.key)
+        else:
+            builder.error("PEP 798 is not supported yet", o.line)
+            k = builder.none()
         v = builder.accept(o.value)
         builder.call_c(exact_dict_set_item_op, [builder.read(d, o.line), k, v], o.line)
 
diff --git a/mypyc/irbuild/prebuildvisitor.py b/mypyc/irbuild/prebuildvisitor.py
index b99a588c34d2..0f2aa7c1c91e 100644
--- a/mypyc/irbuild/prebuildvisitor.py
+++ b/mypyc/irbuild/prebuildvisitor.py
@@ -43,7 +43,8 @@ def _comprehension_has_lambda(node: GeneratorExpr | DictionaryComprehension) ->
     if isinstance(node, GeneratorExpr):
         node.left_expr.accept(checker)
     else:
-        node.key.accept(checker)
+        if node.key is not None:
+            node.key.accept(checker)
         node.value.accept(checker)
     for conds in node.condlists:
         for cond in conds: