Among all the patients treated by the Italian Cooperative Group for TTP, we retrospectively reviewed the results obtained using vincristine (VCR) in 8 TTP patients (4 men and 4 women, average age: 39.25 years, range: 23-48) who did not respond to combined apheretic and pharmacologic treatment. All patients, after failing to respond to treatment, were started on VCR at the dose of 2 mg, i.v., once a week. Despite this treatment, 4 patients (50%) died 1, 7, 12 and 25 days after the first VCR dose, respectively. The other 4 patients who received VCR achieved complete remission 24, 30, 40 and 50 days from the beginning of the treatment. Total doses of VCR ranged from 2 to 6 mg in the decreased group, and from 6 to 14 mg in the cured patients. In our experience, VCR is a promising agent to treat TTP patients resistant to conventional plasma-exchange and pharmacologic therapy.