Serial thyroid functions studies were carried out in patients with melanoma and renal cell carcinoma treated with interleukin-2 (3 MU m-2 by continuous infusion days 1-4) and interferon alpha-2a (6 MU m-2 subcutaneously on days 1 and 4), both given on alternate weeks. This evidence concerns the gene IL2 and hereditary clear cell renal cell carcinoma.