The authors studied 297 patients with multiple sclerosis (MS), correlating urinary symptoms (bowel/bladder Functional System [FS] score of the Expanded Disability Status Scale [EDSS] and bladder dysfunction score of the Guy's Neurological Disability Scale [GNDS[) vs objective measurement of bladder dysfunction (postmicturition residual volume). EDSS and GNDS were of no value for predicting the presence of a clinically relevant postvoiding volume. Therefore, the authors recommend ultrasound scanning of residual volume in every patient with MS, even in the absence of subjective urinary symptoms.