Surgical site infections are the second or third most common type of nosocomial infections in Germany. For hospitals an annual incidence of 130000-160000 cases is estimated. Microbiological findings basically depend on type of surgery and wound location. A variety of risk factors is known. Discrimination of avoidable and unavoidable risk factors is the key for prevention. Most important points in prevention are perioperative prophylaxis with antibiotics 30-60 minutes prior to incision and strict asepsis in the operation room. Clinical findings include a variety of symptoms. They can be assigned to an early course or a definitive infection. However, wound scores are better applicable when comparing clinical studies. The most important therapeutic procedure is clearing the source of infection. Subsequently the wound can be closed by secondary intention or lead to open wound healing. An accompanying therapy with antibiotics is recommendable in case of advanced local or systemic infection. To document wounds is an essential part of treating wounds.