Objective: No reports have evaluated the treatment effects of tadalafil by age group in a positive, noninterventional observational study of Japanese men. The present study aimed to evaluate the treatment effects of tadalafil by age group in a positive, noninterventional observational study of Japanese men. We therefore divided patients into 2 groups about the age of 70 years and investigated the treatment effects of tadalafil regarding voiding and storage functions by age group. Methods: Changes from baseline in each parameter (International Prostate Symptom Score [IPSS], quality of life [QOL] score, Overactive Bladder Symptom Score [OABSS], and residual urine volume) at 4, 12, and 24 weeks after initiating tadalafil for benign prostatic hyperplasia (BPH) patients were compared between groups (50–69 years vs. ≥70 years). In addition, side effects of tadalafil were investigated by age group. Results: In the 50–69 years group, significant improvements from baseline were seen in IPSS total and QOL score for all time points. In addition, significant improvements in IPSS storage subscore from baseline were observed at the 4- and 24-week time points. In the ≥70 years group, significant improvements from baseline were seen in IPSS total, IPSS voiding and storage subscores, and QOL score at each time point. Conclusions: Tadalafil 5 mg once daily appeared effective in clinical settings for elderly BPH patients even over 70 years old.