In light of some evidence that hormonal factors may impact on malignant melanoma, we performed a randomized trial of megestrol acetate versus observation among 67 patients with high-risk resected stage I or stage II (nodal) malignant melanoma. Following stratification by relevant prognostic factors, we observed a statistical significance in survival advantage for megestrol acetate that approached 7.6 versus 2.6 years, median survival; two-sided log rank p = 0.06. Disease-free survival was also greater for patients who received this hormonal therapy (3.4 versus 1.1 years, median disease-free survival), but the difference was not statistically significant (two-sided log rank p = 0.20). The most noteworthy side effects were weight gain (median 6-month gain of 8.2 kg) and impotence. Fully recognizing the hazards of limited sample analyses and the need for confirmatory trials, our findings suggest a possible role for megestrol acetate as adjuvant therapy for selected patients with malignant melanoma.