Until recently, antimicrobial prophylaxis was thought to be unnecessary for clean surgery except when a foreign body is implanted or the presence of infection poses a significant risk to patients. However, the results of several trials support extending the administration of antimicrobial prophylaxis to other types of clean surgery such as inguinal. hernia repair or breast surgery. A recent Cochrane meta-analysis concluded that antimicrobial prophylaxis for inguinal hernia repair with or without mesh cannot be recommended or discarded. Resolution of this problem is important because inguinal hernia repair with mesh is one of the most common procedures in general. surgery, and antibiotic consumption for preventive purposes is becoming a serious problem due to the risk of contribution to development of bacterial. resistance and the significant increase in healthcare costs. This review will document clinical trials and meta-analyses on clean surgery, and will focus on inguinal hernia repair with mesh. (c) 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.