Thirty-two patients with stage D carcinoma of the prostate were treated with oral estramustine phosphate at a dose of 15 mg/kg/day from 3 to 15 months. Objective remissions, reduction of greater than 50 percent of measurable lesions such as soft tissue masses, lymph nodes, and prostatic masses, were seen in seven of 32 patients (22 percent response rate). Subjective response, ie, relief of pain, weight gain, sense of well being, snd improved performance status, occurred in all objective responders and in seven other patients with stable disease (15 of 32 patients = 47 percent). No hematologic, hepatic, or renal toxic effects were observed. Transient nausea occurred early in one half of the patients and nausea and vomiting was dose limiting in only two patients. Oral estramustine phosphate is well tolerated and worthy of further clinical use.