Index: Lib/_pyio.py
===================================================================
--- Lib/_pyio.py	(revision 71243)
+++ Lib/_pyio.py	(working copy)
@@ -319,16 +319,11 @@
     __closed = False
 
     def close(self) -> None:
-        """Flush and close the IO object.
+        """Close the IO object.
 
         This method has no effect if the file is already closed.
         """
-        if not self.__closed:
-            try:
-                self.flush()
-            except IOError:
-                pass  # If flush() fails, just give up
-            self.__closed = True
+        self.__closed = True
 
     def __del__(self) -> None:
         """Destructor.  Calls close()."""
Index: Lib/test/test_io.py
===================================================================
--- Lib/test/test_io.py	(revision 71243)
+++ Lib/test/test_io.py	(working copy)
@@ -397,13 +397,10 @@
             def close(self):
                 record.append(2)
                 super().close()
-            def flush(self):
-                record.append(3)
-                super().flush()
         f = MyFileIO(support.TESTFN, "wb")
         f.write(b"xxx")
         del f
-        self.assertEqual(record, [1, 2, 3])
+        self.assertEqual(record, [1, 2])
         f = open(support.TESTFN, "rb")
         self.assertEqual(f.read(), b"xxx")
 
@@ -417,7 +414,6 @@
                 # function, not by __del__)
                 self.on_del = 1
                 self.on_close = 2
-                self.on_flush = 3
             def __del__(self):
                 record.append(self.on_del)
                 try:
@@ -429,12 +425,9 @@
             def close(self):
                 record.append(self.on_close)
                 super().close()
-            def flush(self):
-                record.append(self.on_flush)
-                super().flush()
         f = MyIO()
         del f
-        self.assertEqual(record, [1, 2, 3])
+        self.assertEqual(record, [1, 2])
 
     def test_IOBase_destructor(self):
         self._check_base_destructor(self.IOBase)
Index: Modules/_io/iobase.c
===================================================================
--- Modules/_io/iobase.c	(revision 71243)
+++ Modules/_io/iobase.c	(working copy)
@@ -130,7 +130,7 @@
 }
 
 PyDoc_STRVAR(IOBase_close_doc,
-    "Flush and close the IO object.\n"
+    "Close the IO object.\n"
     "\n"
     "This method has no effect if the file is already closed.\n");
 
@@ -169,27 +169,16 @@
 }
 
 /* XXX: IOBase thinks it has to maintain its own internal state in
-   `__IOBase_closed` and call flush() by itself, but it is redundant with
-   whatever behaviour a non-trivial derived class will implement. */
+   `__IOBase_closed` but it is redundant with whatever behaviour a non-trivial
+   derived class will implement. */
 
 static PyObject *
 IOBase_close(PyObject *self, PyObject *args)
 {
-    PyObject *res;
-
     if (IS_CLOSED(self))
         Py_RETURN_NONE;
 
-    res = PyObject_CallMethodObjArgs(self, _PyIO_str_flush, NULL);
     PyObject_SetAttrString(self, "__IOBase_closed", Py_True);
-    if (res == NULL) {
-        /* If flush() fails, just give up */
-        if (PyErr_ExceptionMatches(PyExc_IOError))
-            PyErr_Clear();
-        else
-            return NULL;
-    }
-    Py_XDECREF(res);
     Py_RETURN_NONE;
 }