By means of a randomized, controlled and open study the authors wanted to find out if cerebrospinal (CSF)-filtration was of substantial benefit to patients with sporadic amyotrophic lateral sclerosis (SALS). Five SALS patients, aged 51-75 years, being treated with riluzole underwent CSF-filtration daily over five days (group A). Five other SALS patients, aged 52-70 years, were treated only with riluzole (group B). Although all five patients in the first group reported a subjective benefit following CSF-filtration, the Norris score, the Frenchay score, the vital capacity, the ulnar nerve F-wave persistence and the peak-ratio of the brachial biceps and anterior tibial muscles did not change significantly after five days of therapy either in group A or in group B. In conclusion, filtration of 200-250 mi CSF daily, over five days, does not seem to have a substantial therapeutic effect in patients,vith SALS. Eur J Neurol 6:597-600 (C) 1999 Lippincott Williams & Wilkins.