A prospective phase II trial was carried out to define the activity of a low-dose subcutaneous regimen of interleukin-2 (IL-2) and interferon alpha-2b (IFN-alpha) in combination with intravenous administration of vinblastine (VLB) in patients with metastatic renal cell cancer (RCC). Thirty-one patients with advanced RCC who had received no prior biochemotherapy were treated with IL-2 4.5 MU x 2/24 h thrice weekly for 2 weeks, IFN-alpha 3 MU/24 h thrice weekly (alternating days) for 2 consecutive weeks and VLB 4 mg/m2 every 3 weeks. Patients were to have a 1-week rest period after each 2 weeks of therapy with cytokines. Treatment was repeated every 3 weeks. Maximum duration of treatment was 1 year. Treatment was administered on an outpatient basis. There were 4 complete (12.9%) and 8 partial responses (25.8%), with an overall response rate of 38.7%. The median duration of response was 6.5 months. Responses were seen in lung, lymph nodes, bones, liver and other tumor metastases. Toxicity was mild to moderate, consisting of fever, anorexia, malaise and nausea-vomiting in>> 80% of patients. Hypotension and transient alopecia occurred in>> 20% of patients. Liver enzyme elevation was frequently observed. Treatment-induced eosinophilia occurred in the majority of patients, while in 52% of patients granulocytopenia grade II and grade III did not require dose modification of drugs. Transient inflammation and local induration at the injection sites was observed in the majority of patients. None of the patients experienced major VLB-related toxicity and no toxic deaths occurred. This three-drug combination immunochemotherapy may be a promising regimen with modest toxicity in advanced RCC.