Objectives: Combination therapy of benign prostatic hyperplasia (BPH) with an α-blocker plus a 5α-reductase inhibitor significantly reduces the risk of clinical progression of BPH more than treatment with either drug alone. We aimed to determine whether the α-blocker could be discontinued at 6 or 9 months after initiating the combination therapy without symptoms worsening. Materials and Methods: This open-label study, conducted at 19 urological clinics in Taiwan, enrolled 1187 outpatients with BPH-associated, obstructive lower urinary tract symptoms and a prostate volume of ≥20 g or a maximum urinary flow rate of <15 ml/s. Eligible patients, who had never received treatment or had received only an α-blocker for BPH, were given 5 mg finasteride daily and an α-blocker and were randomly assigned to discontinue the α-blocker at either 6 or 9 months. Results: All efficacy measures, including prostate volume, maximum urinary flow rate, and International Prostate Symptom Score (IPSS), significantly improved (p<0.05) from the baseline to month 6. In total, 658 patients (55.4%) were evaluated for success at 1 month after discontinuing the α-blocker therapy. Success was defined as no deterioration in the IPSS or no need to restart the α-blocker at 7 or 10 months. The success rate was significantly higher among those patients receiving 9 compared to 6 months of combination therapy (70% vs. 62%; p=0.0254, by Chi-square test). Conclusions: Most patients (70%) could successfully discontinue the α-blocker after 9 months of combination therapy. Simplifying the treatment regimen for BPH can reduce medication costs and may possibly increase patient compliance.