Using the trial demonstrating that interferonalpha-2a (IFNalpha-2a) is efficacious as adjuvant therapy in stage II melanoma, we evaluate its outcomes and economic consequences. Using rates observed in the 5-year trial and published figures, survival and Q-TWIST (Time Without Symptoms and Toxicity) were extrapolated to a 10-year and lifetime horizon. Cost analysis was performed using the trial's data, published literature and experts' opinions from the perspective of the French Sickness Funds. Patients in the IFNalpha-2a-group have an additional 0.26 years in life-expectancy over a 5-year time period (P=0.046), 0.67 years over a 10-year period and 2.59 years over a lifetime. Cost per life-year-gained was estimated at approximately 14400 after 5 years, 6635 after 10 years and 1716 over a lifetime. Assuming that there is an improvement in disease-free survival only, cost is 26147 per Q-TWIST. Cost-effectiveness of IFNalpha-2a in stage II melanoma compares favourably with estimates for widely used therapies in the oncological field.