Intramuscular and intranasal synthetic salmon calcitonin (sCT) has long been used in the treatment of involutional osteoporosis. A new suppository formulation was developed and many studies demonstrated that rectally administered sCT is efficacious and well tolerated. Thirty postmenopausal women, who had a bone mineral density at the lumbar spine below the mean of age-matched women, were enrolled in this study. Using an open balanced, randomized design, the patients were allocated to two groups of treatment: sCT suppositories at the dose of 100 UI/day or 200 UI every other day for six months. Treatment with sCT suppositories caused a statistically significant decrease of pain in both study groups. Bone mineral density at lumbar spine showed an increase in both study groups with significant difference respect the basal value for the patients treated with sCT on alternate day. Based on the results of this study, we can thus conclude that sCT in suppository formulation is effective in reducing pain sintomatology, bone loss and turnover in involutional osteoporosis.