Irrigation and debridement (I and D) is a procedure commonly used for the treatment of acute periprosthetic infection. This study retrospectively reviewed clinical records of patients with periprosthetic infection of the hip or knee who underwent I and D with retention of their prostheses between 1997 and 2005 at a single institution. One hundred four patients (44 males and 60 females) were identified. Mean age at time of initial debridement was 65 years. Average follow-up was 5.7 years. Treatment failure was defined as the need for resection arthroplasty or recurrent microbiologically proven infection. According to these criteria, I and D was successful in 46 patients (44%). Patients with staphylococcal infection, elevated American Society of Anesthesiologists score, and purulence around the prosthesis were more likely to fail. The high failure rate of this procedure implies that it should be preferably limited to select healthy patients with low virulence organisms and equivocal intraoperative findings. © 2010 Elsevier Inc.