Malignant melanoma occurs in approximately 1.7 per cent of all patients admitted to the Clinical Center, National Institutes of Health, and approximately 1.8 per cent of patients admitted with hypercalcemia and malignant disease. The incidence of hypercalcemia and malignant melanoma is 1.1 per cent. Bone metastases are diagnosed before death in approximately 5.2 per cent of patients with malignant melanoma. The cause of hypercalcemia in our patients appears to be bone metastases in 83.3 per cent and primary hyperparathyroidism in 16.9 per cent.