We evaluated the efficacy and safety of a1 - blocker doxazosin for treatment of lower urinary tract symptoms (LUTS) compatible with benign prostatic hypertrophy (BPH). Fourteen randomized controlled trials enrolled 6261 men, average age 64 years, who had moderately severe LUTS and flow impairment. Compared with baseline measures and placebo effect, doxazosin resulted in a statistically significant improvement in both LUTS and flow. However, when compared with placebo, the average magnitude of symptom improvement (International Prostate Symptom Score [IPSS] improvement <3 points) typically did not achieve a level detectable by patients. Combined doxazosin and finasteride therapy improved LUTS and reduced the risk of overall clinical progression of BPH compared to each drug separately in men followed over 4 years. Reported mean changes from baseline in the IPSS were −7.4, −6.6, −5.6, and −4.9 points for combination therapy, doxazosin, finasteride, and placebo, respectively. Combination therapy reduced the need for invasive treatment for BPH and the risk of long-term urinary retention. The absolute reductions compared with placebo were less than 4% and primarily seen in men with prostate gland volume >40 mL or PSA levels >4 ng/mL. Efficacy was comparable with other a1–blockers. Withdrawals from treatment for any cause were comparable to placebo. Dizziness and fatigue occurred more frequently with doxazosin compared to placebo.