There is a rising incidence of malignant melanoma world-wide and, despite major improvements in its early diagnosis and treatment, the 10-year death rate remains at 20-25%. Evidence that the immune system has a role in the control of melanoma growth has encouraged immunological intervention. The results of phase II trials of recombinant interferon alfa-2a in advanced melanoma justified further studies. A review of trials of various interferons used as sole agents showed an overall objective response rate of 16.3%, one-third of the responses being complete responses of long duration. The use of cimetidine together with recombinant interferon alfa-2a remains controversial. Trials of both beta- and gamma-interferons are incomplete and information on their effect in advanced melanoma is not yet available. Recombinant interferon alfa-2a in combination with chemotherapy is now being used in trials and the early results are encouraging. In a combined series from Brisbane and Newcastle, Australia involving 44 patients treated with recombinant interferon alfa-2a and DTIC, 13 objective responses including 6 complete responses have been obtained. These response rates compare favourably with those of earlier trials using interferon alone. Further work is necessary to determine the best combined dosage and method of administration for optimum immunobiological effect.