Surgical site infections (SSI) are a major concern in terms of morbidity, mortality and additional costs for the hospital. In developed countries, between 2% and 7% of surgical patients develop an SSI in the month following surgery. This rate exceeds 25% in some developing countries. SSIs have aroused the interest of developed countries. As part of a global approach to the quality of care and patient safety, these countries have rigorously implemented action and control programs against nosocomial infections, of which SSI is a priority. It has been established that this category of infection is the number one preventable nosocomial infection. The definition of SSI has been standardized. The risk of SSI depends on several parameters, the importance of the inoculum, the virulence of the germs and the resistance of the host. Risk factors related to the patient and factors related to the characteristics of the surgical procedure have been identified. Recommendations for the prevention of SSI have been established. Specific preventive measures are mainly based on antibiotic prophylaxis and skin preparation of the patient.