High-dose continuous infusion interleukin-2 (IL-2) regimens generate a higher degree of lymphokine activated killer cell (LAK) cytotoxicity when tested against tumor cells in vitro and a higher rebound lymphocytosis in vivo than do bolus IL-2 regimens. Lymphocytes initially activated by continuous infusion IL-2 have increased cytotoxicity against cancer cells when they are subsequently pulsed with additional IL-2. Famotidine may enhance LAK cytolytic ability. Six patients with kidney cancer have been treated with a combination of famotidine 20 mg intravenous bid and continuous infusion IL-2 (18 MIU/sq m/24 hours) for 72 hours, followed by a 24-hour rest, then IL-2 18 MIU/sq m over 15-30 minutes. The most common metastatic sites were the lung, lymph node, and bone. Median number of cycles received = 5 (range, 3-8). The most common toxicities were fever, rigors, nausea/emesis, hypophosphatemia, hypotension, elevated creatinine, and metabolic acidosis. There were no treatment-related deaths, and no patients required intensive care admission. Two partial responses (33% response rate) have been seen. Median survival has not been reached at greater than 8 months. The combination of high-dose continuous infusion plus pulse IL-2 and famotidine is active in metastatic kidney cancer. An accrual of additional patients is needed to better assess the response rate.