We have performed a translational phase II trial testing an original immunotherapy schedule based on the monthly subcutaneous (s.c.) administration of hrGM-CSF (days 1 through 5) and very low dose hrIL-2 (days 6 through 15) in 19 patients with metastatic renal cell carcinoma. Bone pain, first dose reaction to GM-CSF, asthenia and fever were the most common side effects. A partial response, and a disease stabilization were respectively observed in 4 and 11 cases, with a rate of objective response and a disease control rate respectively of 21% and 79%. We recorded a time to progression of 9 months and a 2- and 3-year survival respectively of 42% (8/19 patients) and 26% (5/19 patients). Our results suggest that this GM-CSF/hrIL-2 combination is active and well tolerated in patients with renal cell carcinoma and deserves to be investigated in larger comparative trials.