In a phase ii trial 18 previously treated patients with metastatic prostatic carcinoma with measurable or evaluable disease were treated with cisplatin 50 mg/m2 every 3 weeks. Treatment was well tolerated in this elderly group of patients except for GI toxicity seen in 75% of the patients. There were no objective responses. Changes in serum acid phosphatase were often transient and not accompanied by clinical improvement. Cisplatin does not appear to be an effective agent in metastatic prostatic carcinoma in the dose schedule employed.