Forty postmenopausal women with a former Colles' fracture were enrolled in a 1-year study to determine the dose-effect relationship of nasal salmon calcitonin (SCT) on bone mass. They were randomized to receive either placebo, 50, 100, or 200 IU per day of SCT given as a nasal spray. The rate of change in the bone mineral content of the lumbar spine was 0.7, 0.2, 1.1, and 2.0 gHA per year, respectively, and the rate of change in the bone mineral content in the forearm was -0.4, -0.1, 0.0, and -0.1 AU per year, respectively. The rate of change in the bone mineral content of the lumbar spine in patients receiving 200 IU of SCT per day differed significantly from zero (P less than 0.01). Except for one patient, who experienced intolerable nausea, no systemic side effects were observed. Seven patients withdrew, two patients from nasal intolerance to the spray. These preliminary data suggest that SCT given by the nasal route has a positive and dose-dependent effect on spinal bone mass, but affects forearm bone mass only minimally.