Nosocomial infections are frequent complications after abdominal surgery. Most abdominal procedures are clean-contaminated, contaminated, or even dirty procedures, since plenty of microorganisms are able to enter the gastrointestinal and the genitourinary tracts. Nosocomial infections are associated with morbidity and mortality and reduce patients' quality of life after surgery. Moreover, they prolong hospital stay and altogether represent an economic burden for health services. Despite different guidelines endorsed by scientific societies describing recommendations for preventing and treating nosocomial infections, they still represent a challenge for healthcare staff. The aim of this book is to revise the actual evidence on the different aspects of nosocomial infections after abdominal surgery.