The effects of α1-adrenergic blockade with prazosin HCl were examined in 28 patients with benign prostatic hypertrophy and bladder neck contracture. The patients received 2–3 mg of prazosin HCl daily administered orally. Improvement in subjective symptoms was observed in 75% of the patients. We evaluated clinical effects as the minimum time of micturition (calculated as the ratio of voided volume/maximum flow rate) for voided volumes less than 200 ml and the maximum flow rates and average flow rates for voided volumes over 200 ml. Evaluation of the findings on a flow rate nomogram revealed improvement in maximum flow rates and average flow rates in 41% of the patients. Side effects such as dizziness developed in only 1 patie