We treated 14 patients (4 malignant melanoma/10 renal carcinoma) with a combination of continuous infusion interleukin-2 (IL-2) and subcutaneous alpha-interferon. Variable concentrations of albumin were added to the infusion of IL-2. The toxicity of this regimen seems to be related to the percentage of albumin added to the IL-2 infusion. Partial responses were observed in 3 cases. Interestingly, 1 patient's response appeared dependent on the addition of human serum albumin. The mechanism of these effects is unknown, but the use of albumin with IL-2 should be carefully investigated in future studies.