diff -r 0eeffeadaa1e Lib/test/test_array.py
--- a/Lib/test/test_array.py	Mon Aug 06 17:53:19 2012 -0700
+++ b/Lib/test/test_array.py	Tue Aug 07 11:44:05 2012 +0200
@@ -1015,6 +1015,19 @@
         a = array.array('H', b"1234")
         self.assertEqual(len(a) * a.itemsize, 4)
 
+    @support.cpython_only
+    def test_sizeof_with_buffer(self):
+        a = array.array(self.typecode, self.example)
+        basesize = support.calcvobjsize('Pn2Pi')
+        buffer_size = a.buffer_info()[1] * a.itemsize
+        support.check_sizeof(self, a, basesize + buffer_size)
+
+    @support.cpython_only
+    def test_sizeof_without_buffer(self):
+        a = array.array(self.typecode)
+        basesize = support.calcvobjsize('Pn2Pi')
+        support.check_sizeof(self, a, basesize)
+
 
 class StringTest(BaseTest):
 
diff -r 0eeffeadaa1e Modules/arraymodule.c
--- a/Modules/arraymodule.c	Mon Aug 06 17:53:19 2012 -0700
+++ b/Modules/arraymodule.c	Tue Aug 07 11:44:05 2012 +0200
@@ -1567,6 +1567,19 @@
 an array of some other type.");
 
 
+static PyObject *
+array_sizeof(arrayobject *self, PyObject *unused)
+{
+    Py_ssize_t res;
+    res = sizeof(arrayobject) + self->allocated * self->ob_descr->itemsize;
+    return PyLong_FromSsize_t(res);
+}
+
+PyDoc_STRVAR(sizeof_doc,
+"__sizeof__() -> int\n\
+\n\
+Size of the array in memory, in bytes.");
+
 
 /*********************** Pickling support ************************/
 
@@ -2143,6 +2156,8 @@
      tobytes_doc},
     {"tounicode",   (PyCFunction)array_tounicode,       METH_NOARGS,
      tounicode_doc},
+    {"__sizeof__",      (PyCFunction)array_sizeof,      METH_NOARGS,
+     sizeof_doc},
     {NULL,              NULL}           /* sentinel */
 };