The analgetic effect of 100 IU of Calcitonin was studies in a double blind study in patients with bone metastases from breast cancer. The performance status and side effect were further interest of the study. 60 patients were e rolled in the study, 55 evaluated. In 53% of patients receiving Calcitonin a positive analgetic effect was evaluated, compared with only 22% of place group. The side effects were minimal. The survival time was not influced by Calcitonin therapy.