diff -r c820aa9c0c00 Modules/_struct.c
--- a/Modules/_struct.c	Fri Apr 20 18:04:03 2012 -0400
+++ b/Modules/_struct.c	Mon Apr 23 16:57:18 2012 +0300
@@ -1752,6 +1752,19 @@
     return PyLong_FromSsize_t(self->s_size);
 }
 
+static PyObject *
+s_sizeof(PyStructObject *self, void *unused)
+{
+    Py_ssize_t res;
+    formatcode *code;
+
+    res = sizeof(PyStructObject) + sizeof(formatcode);
+    for (code = self->s_codes; code->fmtdef != NULL; code++) {
+        res += sizeof(formatcode);
+    }
+    return PyLong_FromSsize_t(res);
+}
+
 /* List of functions */
 
 static struct PyMethodDef s_methods[] = {
@@ -1760,6 +1773,8 @@
     {"unpack",          s_unpack,       METH_O, s_unpack__doc__},
     {"unpack_from",     (PyCFunction)s_unpack_from, METH_VARARGS|METH_KEYWORDS,
                     s_unpack_from__doc__},
+    {"__sizeof__",      (PyCFunction)s_sizeof, METH_NOARGS,
+     "Returns size in memory, in bytes"},
     {NULL,       NULL}          /* sentinel */
 };