16 adult idiopathic thrombocytopenic purpura (ITP) patients, with mean age 51 years, were treated by 5 weekly slow intravenous infusions of vinblastine (0.1 mg/kg). When a complete or partial response (CR or PR) was obtained, slow infusions were repeated at 2-weekly then monthly intervals, as maintenance therapy. In 4 cases with ITP of recent onset, but presenting contraindication or failure to prednisone and high dose intravenous immunoglobulins, CR was obtained in all patients after 4 to 15 days (mean 9.5). Only one of these patients relapsed. In 12 cases of refractory chronic ITP (of whom 10 had been splenectomized), there were 2 CR, 6 PR and 4 failures. The 8 responding patients had a mean interval to response of 20 days. The 6 PR were short and did not exceed 15 days. Our results do not support a superiority of this treatment compared to other modes of administration of vinca alkaloids in ITP (intravenous bolus, vinca loaded platelets).