diff --git a/google/cloud/spanner_v1/types/result_set.py b/google/cloud/spanner_v1/types/result_set.py
index 68ff3700c5..2990a015b5 100644
--- a/google/cloud/spanner_v1/types/result_set.py
+++ b/google/cloud/spanner_v1/types/result_set.py
@@ -238,6 +238,20 @@ class ResultSetMetadata(proto.Message):
             If the read or SQL query began a transaction
             as a side-effect, the information about the new
             transaction is yielded here.
+        undeclared_parameters (google.cloud.spanner_v1.types.StructType):
+            A SQL query can be parameterized. In PLAN mode, these
+            parameters can be undeclared. This indicates the field names
+            and types for those undeclared parameters in the SQL query.
+            For example, a SQL query like
+            ``"SELECT * FROM Users where UserId = @userId and UserName = @userName "``
+            could return a ``undeclared_parameters`` value like:
+
+            ::
+
+                "fields": [
+                  { "name": "UserId", "type": { "code": "INT64" } },
+                  { "name": "UserName", "type": { "code": "STRING" } },
+                ]
     """
 
     row_type = proto.Field(
@@ -250,6 +264,11 @@ class ResultSetMetadata(proto.Message):
         number=2,
         message=gs_transaction.Transaction,
     )
+    undeclared_parameters = proto.Field(
+        proto.MESSAGE,
+        number=3,
+        message=gs_type.StructType,
+    )
 
 
 class ResultSetStats(proto.Message):