Low doses of recombinant alpha 2-interferon were administered to 20 patients with stage III malignant melanoma. Dosage was 2.5 million IU intramuscularly daily in the first four weeks, then 2.5 million IU twice a week. The treatment was well tolerated, but there was no definitely demonstrable therapeutic effect. Only two patients are still alive (average survival time of the patients who died was 24 +/- 15 weeks). When there were distant organ metastases at the onset of treatment, survival time was 16 +/- 8 weeks, in case of distant skin metastases 37 +/- 16 weeks. Comparison of this group with a previously treated "control" group indicated that patients treated with interferon have a shorter survival time. However, all of them were far advanced cases with already shortened life expectancy, so that any comparison with the control group is limited.