The objective of this study was to assess the incidence of infection in patients with cutout after proximal femur fracture (PFF) osteosynthesis. Retrospective cohort study. Third-level trauma center. Patients presenting with a cutout following PFF (OTA/AO 31A) osteosynthesis, between January 2007 and December 2020. The primary outcome was infection according to the European Bone and Joint Infection Society criteria. Sixty-seven patients presenting with a cutout were included, with mean age of 83.3 years (range 63-96), and 51 (76.1%) were women. Of all cases, 16 (24.7%) presented a concomitant infection. The presence of concomitant infection was suspected preoperatively in only 3 of the cases. A subgroup analysis was performed between the cases with infection and those without infection, the groups being comparable in terms of demographic data and postoperative radiological criteria. Patients with underlying infection had a higher rate of surgical wound complication (56.3% vs. 22%, P = 0.014) and higher rates of leukocytosis (11.560 vs. 7.890, P = 0.023). Faced with a cutout after osteosynthesis of a PFF, underlying infection should be considered as a possible etiological factor. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.