Patients treated with high-dose or long-term corticosteroids are at risk of accelerated osteoporosis and spontaneous vertebral and traumatic fractures. To assess the efficacy of salmon calcitonin in preventing corticosteroid- induced osteoporosis, 48 patients with newly diagnosed polymyalgia rheumatica, temporal arteritis, and other vasculitides were enrolled in a 2-year, double-blind, randomized, controlled trial. Patients were randomized to receive subcutaneous injections t.i.w. of either 100 IU of salmon calcitonin (25 patients) or placebo (23 patients). After 2 years, 19 and 21 patients, respectively, were evaluable. All patients also received supplemental calcium carbonate (1500 mg daily in divided doses) and vitamin D3 (400 IU daily). Baseline and serial radiologic assessments included dual-energy X-ray absorptiometry (DXA) of the lumbar spine and hip, and spine radiographs to detect vertebral fractures. There were no significant baseline differences between the two study groups. The mean within-subject percentage change in DXA lumbar spine density in the two groups over the 2-year period of the study was only -0.1% (calcitonin plus calcium) versus -0.2% (placebo plus calcium) a nonsignificant difference despite the high mean cumulative corticosteroid doses of 5371 mg and 4680 mg, respectively (NS). The incidence of vertebral fracture was 12.5% (calcitonin plus calcium: 11%, versus placebo plus calcium: 14%, NS), with four fractures in the first year and one fracture in the second year. Higher cumulative cortico-steroid dose was associated with a greater loss in bone density. In rheumatic disease patients starting high-dose, long-term corticosteroids, salmon calcitonin with calcium and vitamin D3 provided no greater bone preservation than that observed with calcium and vitamin D3 alone.