Despite all the efforts made in the areas of intensive care and surgery, severe peritonitis remains a feared condition that is associated with a high mortality rate. Severe abdominal infections are accompanied with a high level of endotoxin production, resulting in the so called systemic inflammatory response syndrome (SIRS), which is often complicated by multiple organ failure. The surgical eradication of the infectious focus is the most important prerequisite for a successful treatment. According to the severity of the local inflammation, different forms of abdominal lavage can be applied. We analysed patient characteristics and the clinical outcome of 180 patients with diffuse peritonitis, including 36 patients with more than 29 MPI-Points. The mean severity of peritonitis (n = 36) was 33 using the Mannheim Peritonitis Index (MPI). The hospital mortality rate was 58 % in this group.