Thirty patients with advanced renal cell carcinoma (RCC), 23 of whom had distant metastases in at least one organ, were entered after nephrectomy into a protocol involving vaccination with Newcastle disease virus (NDV)-modified autologous tumour material, with a subsequent induction week and repetitive bi-weekly cycles of interleukin-2 (rIL-2) and interferon ~2b /rlFN-a~b at a lower s.c. dose (1.5 million Cetus units m -2 day-" every 12 h on 2 days and 3 million IU/m 2 once a day on days 1, 3 and 5). The inpatient treatment was followed by a maintenance phase during which 0.3 million Cetus units/m 2 rlL-2 was given s.c. every 12 h on days 1 -5 and 3 million IUm -2 day -1 rlFN-~zb was administered on days 1, 3, and 5 on an outpatient basis. All but 3 patients completed the induction week and 6 weeks of outpatient therapy. No grade 3 or 4 toxicities occurred during the therapy. Therapy was discontinued for 3 patients because of rapid tumour progression. Of the 23 evaluable RCC patients, 3 exhibited a complete response and 4 displayed partial remission, 7 showed stable disease during 1-18 months (median = 5 months) of therapy, and progression was seen in 9. We conclude that vaccination with autologous tumour material combined with s.c. rIL-2 and rIFN-ctzb administration can induce regressions in patients with advanced RCC and that even in non-responding patients a more favourable course of the disease can be achieved.