diff --git a/src/sage/schemes/generic/scheme.py b/src/sage/schemes/generic/scheme.py
index 2c0e3100c86..7912a5b9b00 100644
--- a/src/sage/schemes/generic/scheme.py
+++ b/src/sage/schemes/generic/scheme.py
@@ -49,6 +49,8 @@ def is_Scheme(x):
         sage: is_Scheme(X)
         True
     """
+    from sage.misc.superseded import deprecation
+    deprecation(99999, "the function is_Scheme is deprecated; use 'isinstance(..., Scheme)' or categories instead")
     return isinstance(x, Scheme)