Testosterone was administered to five patients suffering from metastases in carcinoma of the prostate. In each case the patient had diffuse metastatic lesions in bones and was no longer responding to estrogens, castration, or steroids. The testosterone was given in an attempt to stimulate bone and tumor metabolism and also to enhance the uptake of radioactive phosphorus for a therapeutic effect. The results are exemplified in the case of a man, aged 59 years, with bony metastases that had resulted in multiple fractures of ribs and vertebrae. After five days of treatment with testosterone, he received 2 mc. of radioactive phosphorus (P32) every other day to a total of 20 mc. The beneficial effects were striking though temporary; it was not until the fourth month than any pain returned.