Patients with severe multiple sclerosis (MS) relapses which do not respond sufficiently to corticosteroids can undergo escalating immunotherapy with plasma exchange. We review the course of 14 apheresis cycles in 13 adult patients and three pediatric cases from our center between 2004 and 2005. Nine cases were due to optic neuritis, five had experienced clinically isolated syndromes, and two suffered from Devic's disease. Of the adult patients, 71% had good or very good outcome. The mean time point of improvement was after the third plasmapheresis session, and early initiation of plasma exchange therapy (within 1 month after begin of relapse) was associated with better outcome. In pediatric MS, two of three patients showed clear improvement. These data argue for a very good therapeutic effect of plasma exchange if performed early and with adequate indication.