Hypercalcemia developed in a patient undergoing long-term hemodialysis, and she was found to have noncaseating granulomas on lymph node biopsy. Hydroxychloroquine was administered as therapy for the hypercalcemia. Over 24 weeks of treatment with the drug, concentrations of calcium and 1,25-dihydroxyvitamin D returned to normal. The results demonstrate the capacity of hydroxychloroquine to inhibit the conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D, and emphasize the efficacy of hydroxychloroquine as an alternate to corticosteroids in the treatment of hypercalcemia of granulomatous disease. Hydroxychloroquine may be preferred when existing skeletal disease, or a predisposition to osteopenia, provides relative contraindications to corticosteroid therapy.