PURPOSE We prospectively studied the effect of finasteride on chronic hematuria associated with benign prostatic hyperplasia. MATERIALS AND METHODS We prospectively evaluated 57 patients with chronic intermittent hematuria who were randomized to a finasteride treated or a control arm. RESULTS In the untreated control group hematuria recurred in 17 patients (63%) within a year but in only 4 (14%) in the finasteride group, which was a statistically significant difference (p <0.05). Surgery was required for bleeding in 7 controls (26%), while no patient on finasteride required surgery. CONCLUSIONS Hematuria secondary to prostatic bleeding may be significant if not treated. Finasteride appears to be effective for suppressing hematuria caused by benign prostatic hyperplasia and should be considered as treatment.