There is no good evidence that division of the filum terminale with simultaneous removal of the central spur in patients with diastematomyelia improves their eventual neurological status. We describe 5 patients in whom the filum was not divided and who were later reported upon because of lack of improvement or because of increasing neurological deficit. In 3 patients the division of a congenitally short filum terminale resulted in no improvement; in the other 2, symptoms were relieved following the division of adhesions at the site of previous surgery.