Under analysis are results of treatment of 178 patients with diffuse forms of peritonitis for 2 periods. In the 1st period only one-step sanitation, drainage of the abdominal cavity and naso-gastral aspiration of the gastric content were performed. Lethality was 24.4%. In the 2nd period in the reactive phase of peritonitis a one-step sanitation, naso-gastral aspiration were performed, in the toxic and terminal periods--fractional peritoneal lavage and decompression of the intestines through ceco- and ileostomy. Lethality was 6.3%.