Surgical site infection (SSI) is one of the most frequent complications after abdominal surgery as abdominal procedures are often clean-contaminated, contaminated or even dirty procedures, so long the gastrointestinal tract, plenty of microorganisms, is entered. SSI is associated with morbidity and mortality, and reduces the patients' quality of life after surgery. Moreover, it prolongs hospital stay and requires increased instrumentation, medication and complementary tests, altogether representing an economic burden for the Health Services. This has led to the development of several Guidelines and Consensus documents, including prophylactic measures to prevent SSI. Different scientific societies, including the World Health Organization (WHO), the Center for Disease Control (CDC), the American College of Surgeons (ACS) and the Surgical Infection Society (SIS), have published recommendations for the prevention of SSI in the last years. All the documents agree with most of the recommendations. However, the evidence grade of these recommendations is often low to moderate and with the aim to generalise these measures to all the surgical procedures, the extrapolations lead to a lowered evidence power. Thus, in some cases the force of the recommendations is based on the opinion of experts in the field. The aim of this book is to revise the actual evidence about these prophylactic measures in abdominal surgery.