Postoperative complications occur in 10% of patients following major visceral surgery. Of these more than 80% are surgical complications, more than 70% are septic complications and more than 60% are related to anastomotic leakage which accounts for the majority of postoperative deaths. To achieve successful management, early diagnosis is mandatory in cases of deviations from the normal postoperative course. Sufficient external drainage of the leakage and prevention of further contamination across the leakage by gastrointestinal contents are the primary therapeutic goals. The spectrum of therapeutic options is different and depends on the location of the leakage in the gastrointestinal tract. In the surgical treatment of peritonitis, the fundamental requirements for successful management are early detection of persistent abdominal sepsis and of newly developing abdominal complications during the treatment. Furthermore early initiation of effective antibiotic concepts is mandatory.