diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index c905cddc6cba62..4b02ecddd63b27 100644
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -556,6 +556,9 @@ Deprecated
   coroutine.
   (Contributed by Irit Katriel in :gh:`81137`.)
 
+* Deprecate undocumented :func:`!pydoc.ispackage` function.
+  (Contributed by Zackery Spytz in :gh:`64020`.)
+
 
 Pending Removal in Python 3.14
 ------------------------------
diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 83c74a75cd1c00..96aa1dfc1aacf6 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -345,6 +345,8 @@ def sort_attributes(attrs, object):
 
 def ispackage(path):
     """Guess whether a path refers to a package directory."""
+    warnings.warn('The pydoc.ispackage() function is deprecated',
+                  DeprecationWarning, stacklevel=2)
     if os.path.isdir(path):
         for ext in ('.py', '.pyc'):
             if os.path.isfile(os.path.join(path, '__init__' + ext)):
diff --git a/Lib/test/test_pydoc.py b/Lib/test/test_pydoc.py
index 982ee60c0be4f7..99b19d01783a10 100644
--- a/Lib/test/test_pydoc.py
+++ b/Lib/test/test_pydoc.py
@@ -745,14 +745,18 @@ def test_splitdoc_with_description(self):
 
     def test_is_package_when_not_package(self):
         with os_helper.temp_cwd() as test_dir:
-            self.assertFalse(pydoc.ispackage(test_dir))
+            with self.assertWarns(DeprecationWarning) as cm:
+                self.assertFalse(pydoc.ispackage(test_dir))
+            self.assertEqual(cm.filename, __file__)
 
     def test_is_package_when_is_package(self):
         with os_helper.temp_cwd() as test_dir:
             init_path = os.path.join(test_dir, '__init__.py')
             open(init_path, 'w').close()
-            self.assertTrue(pydoc.ispackage(test_dir))
+            with self.assertWarns(DeprecationWarning) as cm:
+                self.assertTrue(pydoc.ispackage(test_dir))
             os.remove(init_path)
+            self.assertEqual(cm.filename, __file__)
 
     def test_allmethods(self):
         # issue 17476: allmethods was no longer returning unbound methods.
diff --git a/Misc/NEWS.d/next/Library/2020-06-15-23-44-53.bpo-19821.ihBk39.rst b/Misc/NEWS.d/next/Library/2020-06-15-23-44-53.bpo-19821.ihBk39.rst
new file mode 100644
index 00000000000000..ede68106b56ff8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-06-15-23-44-53.bpo-19821.ihBk39.rst
@@ -0,0 +1 @@
+The :func:`!pydoc.ispackage` function has been deprecated.