Surgical site infection (SSI) is a feared complication of any surgical procedure. Despite clear progresses during the last decades, recent studies (some from Switzerland) show that many patients still suffer from SSIs and that SSIs have a huge impact for patients and public health. Thus, the prevention of SSIs must constitute a priority of nosocomial infections control in hospitals. In addition to classical approaches focusing on skin preparation, antibiotic prophylaxis, asepsis, and operative environment, surveillance has proved effective in decreasing the incidence of SSIs. The present paper reviews the principles and the main components of an SSI surveillance program.