The study was carried out to determine the effect of a combination regimen of a small dose of calcitonin added to conjugated estrogens with medroxyprogesterone acetate on vertebral bone mass in early postmenopausal women. Comparisons were made with groups of women on calcitonin alone, on conjugated estrogens with medroxyprogesterone acetate alone, or on no treatment. The study was carried out over a 2-year period. The results of the study suggest that the combined regimen of calcitonin and estrogens increased vertebral bone mass in early postmenopausal women to a greater extent than calcitonin alone or estrogen alone. Increases in vertebral bone mass of 11.2% after 1 year and 9.2% after 2 years were demonstrated using the combined regimen. Both estrogens alone and calcitonin alone were, however, very effective in preventing rapid bone loss in the postmenopausal women studied.