42 patients with advanced renal cell carcinoma were treated with a combination therapy with interferon alpha 2a (mean dosage 16 x 10(6) U i.m. 3 times/week) and vinblastine (0.1 mg/Kg every 21 days). 12 patients (28.5%) had a positive response. Of them 1 presented a complete response (2.38%), 5 a partial response (11.9%) and 6 a stable disease (14.2%). No significant side effects were observed apart from the flu-like syndrome (all patients) and a moderate leukopenia (45.2%). The median duration of responses was 10+ months (range 3-37 months). At 4-year follow-up the median survival time was 16.0 months (range 4-37 months).