Twenty-four patients (9 M and 15 F, age range 51-82) with polymyalgia rheumatica receiving 6-methylprednisolone for a period of 9 months (16 mg/daily/two weeks, 14 mg/daily/two weeks, 12 mg/daily/1 month, 10 mg/daily/1 month, 8 mg/daily/1 month, 6 mg/daily/1 month and 4 mg/daily for the last four months) were randomly assigned to receive either 250HD3 (35 mcg/day for 25 days/month) (Group A) or placebo (Group B) in a double-blind study. All patients also received 500 mg elemental calcium daily. Before and at 3, 6 and 9 months ESR, tenderness on palpation and subjective pain were evaluated. At the same times, mineral metabolism parameters (serum calcium, phosphorus, alkaline phosphatase, 24-h urinary calcium, phosphate and 24-h hydroxyproline excretion) and radial bone mineral content (BMC) were evaluated. Activity indexes (ESR and clinical parameters) improved in both groups. Furthermore, serum alkaline phosphatase and 24-h hydroxyproline excretion decreased significantly only in Group A, and BMC decreased significantly in Group B but rose slightly in Group A. No side effects were observed in any of the patients.