Prazosin is well known to most physicians as an effective antihypertensive medication, but its therapeutic value in many cases of benign prostatic hyperplasia (BPH) may be unfamiliar to many. Prostate problems are among the most common medical conditions facing older men, with BPH appearing in more than 50% of men over the age of 50 years and in 90% of those over 80 years of age. About 10% of men over the age of 40 undergo surgery for the condition. Research in the past 15 years has revealed that smooth muscle contractions in the enlarged prostate are controlled by stimulation of the α1-receptors in the tissue. This discovery has provided the rationale for administering drugs to block the stimulation of the αpreceptors to relieve the obstructive and irritative symptoms of BPH. Prazosin was an early candidate for such medication because of its highly selective α1-blockade and its well-documented safety record. Early clinical trials yielded convincing evidence of prazosin’s effectiveness in reducing BPH symptoms, and the number of patients treated with prazosin for BPH now numbers in the several hundreds. In these trials, prazosin administered in doses from 1 mg to as high as 9 mg a day relieved obstructive and irritative symptoms, as well as improved flow rates and decreased urethral pressure. Overall, between 60 and 70% of treated patients can be expected to enjoy real benefits from prazosin the