Circulating levels of calciotropic hormones were measured during one year of treatment with either 200 IU of salmon calcitonin daily or placebo as a nasal spray in 20 postmenopausal women with a former Colles' fracture. A supplement of 0.5 gram elemental calcium was given to all participants. Serum levels of parathyroid hormone and human calcitonin were determined with radioimmunoassays, and serum levels of vitamin D metabolites were determined with protein binding assays. We did not find any significant differences between the two groups with respect to serum levels of calciotropic hormones. In the salmon calcitonin treated group there was a tendency towards a small decrease in serum levels of human calcitonin and an increase in serum levels of calcitriol. Our results suggest that treatment with 200 IU of salmon calcitonin daily as a nasal spray does not markedly affect fasting serum levels of parathyroid hormone, human calcitonin, and vitamin D metabolites.