We present the results of our chemo-biotherapy protocol for patients with metastatic melanoma. The rationale for the design of the combined therapy was induction of systemic anti-tumor immunity by: (a) priming with IFN-alpha for enhancement of tumor and histocompatibility antigen expression, (b) therapy by the 4-drug regimen (BCNU, DTIC, cisplatin and tamoxifen) for maximal tumor destruction, followed by (c) an immunomodulatory, low dose of GM-CSF. Treatment was given in cycles of three weeks: first IFN-alpha (3 x 10(6) U/day on days 1, 3, and 5); then the 4-drug regimen given according to Del Prete et al., (4); followed by GM-CSF (20 micrograms/m2/day on days 15 to 21). All patients were previously untreated by chemotherapy, and had a performance status of ECOG 0-2. Treatment was discontinued upon severe toxicity or disease progression. In responding patients--once maximal response was achieved-IFN alpha treatment (3 x 10(6) U/day, three times weekly) was continued for a period of two years or until disease progression. All 40 patients (28 males and 12 females) who received the above program were evaluable for response and toxicity and received at least two cycles of therapy. At a median follow-up of one year, 50% had achieved an objective response, with 22.5% complete responses (CR), and 27.5% partial remissions (PR). Median duration of response is 11 months (12 for CR and 9 for PR patients). Median survival for all patients is 14 months (range, 7-21), increasing to 22 months (range, 15-29) in responding patients. Activation of patients' peripheral blood Macrophages and Dendritic Cells was observed following GM-CSF treatment. The chemo-biotherapy protocol presented above--while associated with acceptable toxicity--resulted in a relatively high response rate with an increase in the number of durable responses in patients with metastatic melanoma.