In the present study we evaluated the haematological and immunological changes in 4 patients with advanced melanoma and 6 patients with advanced renal cell carcinoma treated with subcutaneous interleukin (IL)-2 and interferon (IFN)-alfa-2b. Serum samples taken before and during six weeks' courses of IL-2 plus IFN-alfa were assayed for the presence of IL-2, soluble IL-2-receptor (sIL-2R), soluble intercellular adhesion molecule-1 (sICAM-1), IL-6 and IL-8. In addition, whole blood counts were taken. Eosinophilia occurred in all patients, lymphocytosis in 8 patients. The higher maximum level of IL-2 during treatment seemed to be connected to longer survival: it was a median of 578 pg/ml in the patients with a median survival of 7 months, and 1025 pg/ml in the patients who survived a median of 15 months. Conversely, an increase in sIL-2R was an unfavourable sign: it was a median of 8-fold and 3-fold in the patients with a median survival of 7 and 16 months, respectively. During treatment, sICAM-1 levels paralleled with those of sIL-2R. There was major intraindividual and interindividual variation in serum IL-6 and IL-8 levels with no distinctive kinetic pattern. Thus, no definite conclusions could be drawn. However, it seems worthwhile to measure IL-2, sIL-2R and sICAM-1 during immunotherapy; their prognostic value should be further evaluated in a larger patient population.