BACKGROUND: The Bernese periacetabular osteotomy (PAO) is a popular option for treating symptomatic acetabular dysplasia. We noted symptomatic impingement after PAO in several male patients. QUESTIONS/PURPOSES: We therefore determined (1) the incidence of clinical signs of FAI after PAO in the male population; and (2) whether any factors were associated with the positive impingement signs after PAO in males. PATIENTS AND METHODS: We retrospectively reviewed 38 males who underwent 46 periacetabular osteotomies (PAO) between 2000 and 2007. Clinical and radiographic data were analyzed with the focus on pre- and postoperative incidence of femoroacetabular impingement. Minimum followup was 12 months (average, 43 months; range, 12-90 months). RESULTS: We found a positive impingement sign in 19 of the 46 hips during the preoperative examination compared to 22 (47.8%) hips postoperatively. The ROM (flexion and internal rotation) decreased postoperatively compared to preoperatively. Radiographic parameters of coverage LCE-, ACE- and Tönnis angle improved into the normal range. Twenty hips had postoperative heterotopic ossification to varying degrees, mostly minor. WOMAC scores improved in the function and pain domains postoperatively. CONCLUSIONS: Despite normalization of coverage we found a high postoperative rate of clinical signs of FAI after PAO in males. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.