Objectives. Inguinal hernias occur in 15% of men within 1 to 2 years after radical retropubic prostatectomy (RRP). This suggests that many of these hernias may have been present at surgery, but not diagnosed. Beginning in September 2001, all patients undergoing RRP were carefully examined intraoperatively for the presence of a hernia or a dilated internal inguinal ring. In this study we define the frequency of inguinal hernias detected at RRP and the durability of repair. Methods. Between September 2001 and December 2004, 430 patients underwent RRP by one surgeon. Hernias, detected in 142 men (33%), were repaired preperitoneally: direct hernias were repaired with mesh and indirect hernias with 2-0 Prolene suture. The patients were followed up for an average of 19 months (range 9 to 36). Information on postoperative hernia status was available for 315 men (73.3%). Results. Of the 430 patients, 142 (33%) had hernias repaired at RRP. Of these hernias, 32% were right sided, 28% left sided, and 40% bilateral; 34% were direct hernias and 66% indirect. Of the 142 patients who underwent intraoperative hernia repair, 95 (67%) had follow-up data, and 5 (5.3%) of that group developed a hernia postoperatively. None of the hernias repaired at RRP recurred. Recurrent hernias on the side of the repair occurred in 3.1%. Conclusions. Incidental inguinal hernias were commonly found (33%) at RRP. Two thirds of the defects detected were indirect. Clinical recurrence after repair was rare.