A 60-year-old man with adult T cell leukemia had been suffering from intractable hypercalcemia resistant to saline hydration, intravenous administration of furosemide, elcatonin, prednisolone and phosphate, and also hemodialysis. Since there was one report suggesting that bleomycin could act as an anticalcemic agent, peplomycin, a new derivative of blerivative of bleomycin, was given at a dose of 10 mg/day by continuous intravenous infusion for 3 days and rapid normalization of serum calcium and creatinine levels resulted. The mechanism of this antihypercalcemic effect is not clear, but peplomycin directly inhibit bone resorption.