Inguinal hernia is one of the long-term complications requiring surgical interventions after retropubic radical prostatectomy (RRP), and its incidence has been reported to range from 12 to 21%. The number of open gasless laparoendoscopic single-site surgery, especially minimum incision endoscopic radical prostatectomy (MIES-RRP) is increasing in Japan. The incidence of post-operative inguinal hernia was compared between conventional RRP and MIES-RRP. The medical records of 333 patients who underwent conventional RRP (n=214) or MIES-RRP (n=119) with pelvic lymphadenectomy at our hospital were retrospectively evaluated. There were no significant differences between the two groups in age, pre-operative PSA levels, or previous major abdominal surgery (cholecystectomy, gastrectomy and colectomy), appendectomy or inguinal hernia repair. MIES-RRP was carried out with a 5-8-cm lower abdominal midline incision. Inguinal hernia developed postoperatively in 41 (19%) of the 214 men undergoing conventional RRP during mean follow-up of 58 months (range: 7-60 months). In contrast, 7 (5.9%) of the 119 men receiving MIES-RRP, developed inguinal hernia during mean follow-up of 21 months (range: 13-31 months). The hernia-free survival was significantly higher after MIES-RRP than after conventional RRP (P=0.037). Our results suggest that MIES-RRP is less associated with post-operative inguinal hernia than conventional RRP.