Purpose: The aim of this study was to evaluate the efficacy of doxazosin over 6 years in men with benign prostatic hyperplasia (BPH). Materials and Methods: This retrospective study enrolled 33 patients with symptomatic BPH who were prescribed an alpha-blocker from January 1999 to December 2000. We evaluated the changes of International Prostate Symptom Score (IPSS), maximal flow rate (Qmax), quality of life (QoL) and residual urine volume (RUV) between before and after 6-year of treatment. Results: The percentages of improvement were 40.2% in total IPSS, 40.6% in obstructive symptom, 39.4% in irritative symptom, 44.7% in QoL, 124.8% in Qmax, 33.5% in RUV (p<0.05). Three patients (9.1%) experienced acute urinary retention and BPH-related surgery was performed in 6 patients (18.2%). Conclusions: Our study revealed that long-term treatment over 6 years with alpha-blocker resulted in significant improvements in the IPSS, QoL, Qmax and RUV.