7 patients with relapsing-remitting multiple sclerosis (MS) were subjected to an intensive course of intravenous (I.V.) cyclophosphamide (CY) therapy. All patients received induction therapy with 11 daily doses of 300 mg/m2 and then a single dose every six months for three years. After one year of follow-up all patients showed a decrease in relapse rate (0.57.57); in the two subsequent years of follow-up 2 patients showed a mild worsening while the others were clinically stable. As suggested by others, our results indicate that I.V. CY therapy may influence the clinical course of relapsing-remitting MS.