Long-term adjuvant therapy of high-risk malignant melanoma with interferon alpha 2b. Fifty-three high-risk melanoma patients in stage I and 15 patients in stage II were treated after standard surgical intervention with adjuvant therapy with recombinant interferon alpha-2b (rIFN alpha 2b) therapy for a total period of 20 months. Concomitant patients (stage I, n = 82; stage II, n = 33) with identical stages and prognostic factors without adjuvant therapy were used to evaluate the efficacy of rIFN alpha 2b therapy. No difference in 5-year relapse incidence and overall survival rates could be detected. However, it appears that patients of both stage I and stage II benefit from long-term adjuvant rIFN alpha 2b therapy, because during the treatment period (20 months), the incidence of relapses was lower in comparison to controls. After stopping treatment the incidence of relapse is equal in treated and control groups. According to the results of our study, we suggest using continuous low-dose rIFN alpha 2b therapy for adjuvant treatment of malignant melanoma. 