diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-06-15-09-37-33.bpo-1572968.zftonM.rst b/Misc/NEWS.d/next/Core and Builtins/2019-06-15-09-37-33.bpo-1572968.zftonM.rst
new file mode 100644
index 00000000000000..e6c296ca2049dc
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-06-15-09-37-33.bpo-1572968.zftonM.rst	
@@ -0,0 +1 @@
+Release the GIL in :class:`mmap.mmap`.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 66ed0b8efb775c..0245a6e04cfafb 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -1562,12 +1562,14 @@ new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
     off_lo = (DWORD)(offset & 0xFFFFFFFF);
     /* For files, it would be sufficient to pass 0 as size.
        For anonymous maps, we have to pass the size explicitly. */
+    Py_BEGIN_ALLOW_THREADS
     m_obj->map_handle = CreateFileMappingA(m_obj->file_handle,
                                            NULL,
                                            flProtect,
                                            size_hi,
                                            size_lo,
                                            m_obj->tagname);
+    Py_END_ALLOW_THREADS
     if (m_obj->map_handle != NULL) {
         m_obj->data = (char *) MapViewOfFile(m_obj->map_handle,
                                              dwDesiredAccess,