Forty-four patients with metastatic cancer of the prostate that had failed conventional hormonal manipulation were treated with high-dose ketoconazole (600-1,200 mg/day). All patients had castrate serum concentrations of testosterone prior to therapy. All of the patients had been assessed by the criteria of the National Prostatic Cancer Project and been categorized as progressing. Over 50% of the patients were recategorized as having stable disease. The majority of the patients showed marked subjective improvement in pain on this therapy. Objective responses were noted but were not consistently seen. Side effects were common but tolerable. The median time of survival was 73.3 weeks. Ketoconazole may be a useful palliative adjunct in the treatment of hormone refractory prostatic cancer.