Forty-two patients with ITP were randomly allocated to vinblastine slow infusion or bolus injection. 16/21 patients (76%) receiving slow infusion of vinblastine and 14/21 patients (67%) receiving a bolus injection of vinblastine had a response. There was no superiority of slow infusions of vinblastine over intravenous bolus injections, either when recently diagnosed and chronic ITP were analysed together or separately. In our opinion, intravenous bolus injections of vinblastine might be preferred, because they are easier to perform and have a better local tolerance.