PURPOSE: The purpose of this study was to evaluate treatment response to terazosin, finasteride, or a combination of both in men with symptomatic benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: Patients with BPH were consecutively enrolled from a clinical urology practice. International Prostate Symptom Score (IPSS), peak urinary flow rate, and prostate volume were assessed at baseline and every 2 months for 12 months. Detrusor pressure at maximum flow was assessed at baseline, 4 and 12 months. Patients were randomized into 1 of 3 treatment groups - terazosin alone, finasteride alone, or combination therapy. RESULTS: At 12 months, symptom scores had decreased significantly in all 3 treatment groups (p<0.05). Combination therapy resulted in significantly greater reductions in IPSS than terazosin or finasteride (6.4, 4.9, 4.1 points, respectively, p<0.05) There were significant increases in peak urinary flow rate within each treatment group, although there were no significant changes between groups. Detrusor pressure also significantly decreased from baseline within each treatment group. Patients treated with combination therapy had a significantly greater mean decrease in detrusor pressure after 12 months when compared with finasteride-treated patients (16.7 versus 10.5 cm H20, p<0.03). There were no significant differences between terazosin and combination therapy or between terazosin and finasteride despite the relatively greater decrease in detrusor pressure seen in the terazosin group when compared with the finasteride group. CONCLUSIONS: Combination medical therapy with finasteride and terazosin provides greater symptom relief than monotherapy in men with BPH.