A woman was admitted for acute renal failure and erythematous lesions. She was diagnosed with sarcoidosis after analysis of biopsy specimens revealed noncaseating epithelioid granulomas, elevated serum angiotensin-converting enzyme levels, and bilateral hilar lymphadenopathy. Serum concentrations of ionized calcium and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] were extremely high. Serum intact osteocalcin concentration and urinary deoxypyridinoline excretion were within reference ranges. Treatment with prednisolone induced a prompt improvement with normalization of serum concentrations of ionized calcium and 1,25-(OH)2D3. Serum intact osteocalcin concentration was markedly suppressed and urinary deoxypyridinoline excretion increased. It is possible suppressed bone resorption may be associated with overproduction of 1,25-(OH)2D3.