The therapeutic application of 89strontium for the relief of pain in 11 cases of carcinoma of the prostate with skeletal metastases is reported. A significant clinical improvement could be observed in 8 of the 11 patients with generalized osseous metastases of prostatic carcinoma after the application of 30 muCi. 89strontium per kg. The effect was long lasting. At the same time an increase of alkaline phosphatase was observed, which was interpreted as an indication of the reactivation of osteoblasts and osteoid peripheral zones owing to beta-emission of the radioisotope in the affected areas. The indications for such therapy are discussed.