BACKGROUND Controversy regarding the relative efficacy of treatments for the relief of the symptoms of benign prostatic hyperplasia (BPH). METHODS This was a 6-month double-blind randomized equivalence study that compared the effects of a plant extract (320 mg Permixon®) with those of a 5α-reductase inhibitor (5 mg finasteride) in 1,098 men with moderate BPH using the International Prostate Symptom Score (IPSS) as the primary end-point. RESULTS Both Permixon® and finasteride decreased the IPSS (−37% and −39%, respectively), improved quality of life (by 38 and 41%), and increased peak urinary flow rate (+25% and +30%, P = 0.035), with no statistical difference in the percent of responders with a 3 ml/sec improvement. Finasteride markedly decreased prostate volume (−18%) and serum PSA levels (−41%); Permixon® improved symptoms with little effect on volume (−6%) and no change in PSA levels. Permixon® fared better than finasteride in a sexual function questionnaire and gave rise to less complaints of decreased libido and impotence. CONCLUSIONS Both treatments relieve the symptoms of BPH in about two-thirds of patients but, unlike finasteride, Permixon® has little effect on so-called androgen-dependent parameters. This suggests that other pathways might also be involved in the symptomatology of BPH. © 1996 Wiley-Liss, Inc.