AIM: To assess the safety profile and efficacy of adjuvant radiation therapy and intermediate-dose interferon in comparison with intermediate-dose interferon alone in patients with synchronous and metachronous skin melanoma metastases in regional lymph nodes with unfavorable prognostic factors. MATERIALS AND METHODS: 96 patients with synchronous and metachronous skin melanoma metastases in regional lymph nodes (stage III according to American Joint Committee on Cancer) and unfavorable prognostic factors were randomized in 2 groups: one of them (n = 45) received regional radiation therapy 50-55 Gy and intermediate dose of α2b-interferon (RT + IFN) in adjuvant setting and another one (n = 51) intermediate dose of α2b-interferon alone (IFN). RESULTS: The most common adverse events in both groups were pyrexia and fatigue but grades 3-4 were observed more frequently in the RT + IFN group than in the IFN group (24.4 and 42.2% vs 11.8 and 27.5% respectively). 3-year recurrence-free survival was 78.5% in the RT + IFN group and 73.8% in the IFN group (p = 0.72), 3-year progression-free survival was 63.2% in the RT + IFN group comparing with 57.2% in the IFN group (p = 0.59) and 3-year overall survival was 77.1% and 66.7%, respectively (p = 0.29). Median of recurrence-free, progression-free and overall survival was not reached in any group. CONCLUSIONS: Radiation therapy and intermediate-dose interferon in adjuvant setting tends to improve recurrence-free, progression-free and overall survival comparing with intermediate-dose interferon alone in patients with synchronous and metachronous skin melanoma metastases in regional lymph nodes and unfavorable prognostic factors but it needs further investigation in larger groups of patients.