In a double-blind study, candicidin therapy resulted in over-all clinical improvement of benign prostatic hypertrophy symptoms in 78.1 per cent of treated patients compared with 10 per cent for patients given a placebo. Histologic review of prostates of candicidin-treated patients showed more stroma relative to the epithelium. The epithelium was less active with more cuboidal than columnar cells. There were fewer papillary infoldings, and the epithelium contained more true cysts than did the prostates of patients given a placebo. Urinary testosterone, 17-ketosteroids, 17-hydroxycorticosteroids, and serum androgen, follicle-stimulating hormones, and corticosteroid levels ramained within normal values with candicidin therapy.