Objective - Chronic administration of corticosteroids has been reported to selectively impair explicit memory in systemic diseases without central nervous system involvement. Our aim was to verify that a short course of pulsed intravenous methylprednisolone (IVMP) administered for the treatment of a relapse impairs cognitive functions in relapsing-remitting multiple sclerosis (RRMS) patients and to determine whether this impairment is reversible. Material and methods - Neuropsychological evaluations were made before the start of treatment, and 7 and 60 days after the end of treatment in 14 RRMS patients. The neuropsychological battery was also administered to 12 controls matched for age, sex and years of education. Results - RRMS patients performed worse than the controls at their baseline evaluation for a variety of neuropsychological tasks. IVMP administration induced a selective impairment of explicit memory which completely recovered 60 days after treatment. Conclusions - In RRMS patients, IVMP induces a selective and reversible impairment of explicit memory. (C) Munksgaard 1998.