OBJECTIVES: I. Evaluate the time to distant metastasis, death due to melanoma, and overall survival in patients with high-risk stage III melanoma treated with 10 MU of interferon alfa (IFN-A) for 4 weeks followed by 1 year of IFN-A at 10 MU three times per week vs. 2 years of IFN-A at 5 MU three times per week vs. observation alone. II. Assess the toxicity associated with IFN-A. III. Compare the quality of life, costs, and compliance associated with each treatment regimen.