diff -r b44eb630bf0a Lib/test/test_io.py
--- a/Lib/test/test_io.py	Mon Apr 16 21:29:58 2012 +0200
+++ b/Lib/test/test_io.py	Mon Apr 16 22:51:00 2012 +0100
@@ -290,7 +290,8 @@
         self.assertEqual(f.tell(), 13)
 
         self.assertEqual(f.truncate(12), 12)
-        self.assertEqual(f.tell(), 13)
+        self.assertEqual(f.truncate(size=11), 11)
+        self.assertEqual(f.tell(), 12)
         self.assertRaises(TypeError, f.seek, 0.0)
 
     def read_ops(self, f, buffered=False):
diff -r b44eb630bf0a Modules/_io/fileio.c
--- a/Modules/_io/fileio.c	Mon Apr 16 21:29:58 2012 +0200
+++ b/Modules/_io/fileio.c	Mon Apr 16 22:51:00 2012 +0100
@@ -882,9 +882,11 @@
 
 #ifdef HAVE_FTRUNCATE
 static PyObject *
-fileio_truncate(fileio *self, PyObject *args)
+fileio_truncate(fileio *self, PyObject *args, PyObject *kwds)
 {
-    PyObject *posobj = NULL; /* the new size wanted by the user */
+    static char *kwlist[] = {"size", NULL};
+    PyObject *posobj  = Py_None; /* the new size wanted by the user */
+    PyObject *posobjk = Py_None; /* the new size wanted by the user */
 #ifndef MS_WINDOWS
     Py_off_t pos;
 #endif
@@ -897,9 +899,19 @@
     if (!self->writable)
         return err_mode("writing");
 
-    if (!PyArg_ParseTuple(args, "|O", &posobj))
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O",
+                                     kwlist, &posobj, &posobjk))
         return NULL;
 
+    /* Fail if both positional and keyword parameters are given */
+    if (posobj != Py_None && posobjk != Py_None) {
+        PyErr_SetString(PyExc_TypeError, "Both positional and keyword 'size' provided");
+        return NULL; 
+    }
+
+    if (posobjk != Py_None)
+      posobj = posobjk;
+
     if (posobj == Py_None || posobj == NULL) {
         /* Get the current position. */
         posobj = portable_lseek(fd, NULL, 1);
@@ -1133,16 +1145,16 @@
 "writable() -> bool.  True if file was opened in a write mode.");
 
 static PyMethodDef fileio_methods[] = {
-    {"read",     (PyCFunction)fileio_read,         METH_VARARGS, read_doc},
+    {"read",     (PyCFunction)fileio_read,     METH_VARARGS, read_doc},
     {"readall",  (PyCFunction)fileio_readall,  METH_NOARGS,  readall_doc},
     {"readinto", (PyCFunction)fileio_readinto, METH_VARARGS, readinto_doc},
-    {"write",    (PyCFunction)fileio_write,        METH_VARARGS, write_doc},
-    {"seek",     (PyCFunction)fileio_seek,         METH_VARARGS, seek_doc},
-    {"tell",     (PyCFunction)fileio_tell,         METH_VARARGS, tell_doc},
+    {"write",    (PyCFunction)fileio_write,    METH_VARARGS, write_doc},
+    {"seek",     (PyCFunction)fileio_seek,     METH_VARARGS, seek_doc},
+    {"tell",     (PyCFunction)fileio_tell,     METH_VARARGS, tell_doc},
 #ifdef HAVE_FTRUNCATE
-    {"truncate", (PyCFunction)fileio_truncate, METH_VARARGS, truncate_doc},
+    {"truncate", (PyCFunctionWithKeywords)fileio_truncate, METH_VARARGS | METH_KEYWORDS, truncate_doc},
 #endif
-    {"close",    (PyCFunction)fileio_close,        METH_NOARGS,  close_doc},
+    {"close",    (PyCFunction)fileio_close,    METH_NOARGS,  close_doc},
     {"seekable", (PyCFunction)fileio_seekable, METH_NOARGS,      seekable_doc},
     {"readable", (PyCFunction)fileio_readable, METH_NOARGS,      readable_doc},
     {"writable", (PyCFunction)fileio_writable, METH_NOARGS,      writable_doc},