The present study aimed to determine the adequate pelvic lymph node dissection (PLND) range for Japanese males undergoing radical prostatectomy. A total of 467 Japanese patients who underwent antegrade radical prostatectomy at the National Kyushu Cancer Center (Fukuoka, Japan) were retrospectively reviewed. The patients were divided into two groups according to the PLND extent: The standard (obturator + internal iliac nodes) group and the expanded (standard + additional nodes) group, which accounted for 64.5% (301/467) and 35.5% (166/467) of the patients, respectively. No differences were observed in the preoperative and postoperative characteristics of the two groups. In addition, there was no difference in PSA recurrence between the two groups. There were no differences between the standard and expanded groups in the low-, intermediate- and high-risk groups (P=0.1456, P=0.1581, P=0.2125, respectively). The median number of lymph node dissection was 13 and 19, in the standard and expanded groups respectively (P<0.0001). However, regarding the number of lymph node metastases and the rate of patients with lymph node metastasis, no significant difference was observed between the standard and expanded groups (P=0.4219 and P=0.4257, respectively). According to multivariate analysis, a significant difference in the presence of lymph node metastasis (hazard ratio 3.547; P=0.0247), but not in the PLND extent, was detected in patients with prostate specific antigen failure (P=0.0655). When expanding the dissection extent, the number of dissected lymph nodes increases, but is not associated with the number or rate of positive lymph nodes. Thus, the current dissection range is considered to be appropriate for Japanese men undergoing radical prostatectomy.