The R3327/MAT-Lu tumor is a metastasizing variant of the Dunning R3327 Copenhagen rat prostatic carcinoma which, when implanted subcutaneously in the flank or intramuscularly in the hind leg, invariably metastasizes to the lungs. We examined treatment with either single dose chemotherapy, surgical excision of the primary tumor, or a combination of tumor excision and postoperative single dose chemotherapy. All 3 regimens significantly reduced the number of lung metastases; however, only the combination of tumor excision, followed by postoperative chemotherapy substantially prolonged survival and produced cures.