To assess the feasibility and toxicity profile of high-dose interferon alpha-2b (IFN-alpha-2b) in the adjuvant treatment of patients with cutaneous malignant melanoma outside the reference ECOG 1684 clinical trial, we conducted a prospective follow-up in an identical population of patients (cutaneous melanoma, T4 and/or N1) treated by intravenous IFN-alpha-2b:20 MIU m(-2), 5 days a week for 4 weeks; and subcutaneous:10 MIU m(-2), 3 times a week for 11 months. Thirty-six consecutive patients were considered in four different institutions. The frequency and severity of side-effects related to IFN-alpha, as well as the percentage of the planned dose given to patients, were identical to those reported in the initial report by ECOG. Fifty per cent and 47% of patients had a grade 3/4 WHO toxicity in the induction and consolidation phase respectively. A dose modification was necessary for 47.2% and 55.8% of the patients in the induction and consolidation phase respectively. The schedule and dose of high-dose IFN-alpha-2b in the adjuvant treatment of cutaneous malignant melanoma, as reported by ECOG 1684, is feasible. The significant toxicity reported in ECOG 1684 was also seen in our patients. Nevertheless, this protocol will not be a 'standard' treatment until the publication of the ECOG 1690 trial.