OBJECTIVES We assessed the efficacy and safety of two α1-adrenoceptor antagonists, tamsulosin and silodosin, in the treatment of male lower urinary tract symptoms. METHODS Men aged 50 years or older who had a total International Prostate Symptom Score (IPSS) of 8 or higher were enrolled in this study. Forty-six patients were randomized into two groups. Twenty-three patients were initially prescribed tamsulosin 0.2 mg once daily for 3 months, followed by silodosin 4 mg twice daily for 3 months (group T); the other group of 23 patients were initially prescribed silodosin, followed by tamsulosin (group S). Patients then switched to the alternative treatment after a 1-month clearance period. Evaluations included clinical determination of IPSS, quality-of-life index, maximum flow rate and postvoid residual urine volume before and after treatment. RESULTS A total of 46 men, 23 in group T and 23 in group S, were treated and 41 (89.1%) completed the treatment. IPSS, quality-of-life index, maximum flow rate and postvoid residual urine volume were significantly improved in both groups after treatment. The changes in the total IPSS from baseline in groups S and T at 3 months were -6.6 and -7.5, respectively. There were no significant differences between the two groups. After taking both medications, 18 patients preferred silodosin, 11 preferred tamsulosin and others felt they had the same effects. Six and none patients experienced adverse events during silodosin and tamsulosin treatment, respectively. CONCLUSION Two types of α1-adrenoceptor antagonists in the same individuals provide similar efficacy. Profiles and difference of each drug should be considered in making treatment choice.