Between 1-1-85 and 6-30-86, 17 patients suffering from metastatic malignant melanoma received total doses of 30-40 I.U. IFN-gamma given i.v. in a daily fractionation of 1.0-2.6 X 10(6) I.U. The only side effect was fever grade I-II (WHO). In four of these patients a regression of the disease was obtained (two complete remissions and two partial remissions, according to UICC criteria). Thus, the overall response rate was 23.5%. The average duration of remission was 8.9 months (range from 1.5 to 21 + months), the average survival time 12.4 months (range from 1.5 to 21 + months, also). Two other patients showed no change lasting for two and five months respectively. In all, systemic interferon-gamma treatment applied in the manner described seems to be able to induce remissions in single cases without showing severe toxicity.