Objectives. To determine the risk factors for postprostatectomy inguinal hernia development. Methods. From January 1998 to June 2004, we investigated the medical records of 201 consecutive patients who had undergone radical retropubic prostatectomy. Postoperatively, 25 (12.4%) of 201 patients developed an inguinal hernia. The preoperative factors, including age, presence of diabetes mellitus, smoking, and previous unilateral hernioplasty, of this group were compared with those of the 176 patients who did not develop an inguinal hernia. The postoperative parameters, including pathologic stage, specimen weight, adjuvant radiotherapy, and postoperative wound-related problems, were compared between the two groups. Results. The patients who had undergone previous unilateral hernioplasty developed a groin hernia after prostatectomy more frequently than those who did not (P = 0.001, Fisher's exact test). Additionally, once a postoperative wound-related problem occurred, the incidence of postprostatectomy groin hernia increased substantially [P = 0.025, logistic regression analysis). Conclusions. We suggest routine repair of the contralateral groin for patients who have undergone previous unilateral hernioplasty. Prevention of wound-related problems appears to decrease the incidence of postprostatectomy groin hernias. ; SCI