Annotation. The aim of the work is to improve the diagnosis and treatment of patients with postoperative peritonitis. The work is based on an analysis of the treatment results of 98 patients who were in the clinic from 2010 to 2019, of which 47 (48%) were admitted to the hospital with a peritonitis clinic, and 51 (52%) had a prolonged bowel paresis in the postoperative period. The diagnosis was established on the basis of data from an objective examination, laboratory parameters and radiation research methods — radiography of the abdominal organs and ultrasound. Based on the analysis of clinical material, it was found that for patients with primary peritonitis, more pronounced clinical symptoms are more characteristic. Postoperative peritonitis in its clinical manifestations proceeds under the mask of a protracted intestinal paresis. Due to the ultrasound criteria of 51 patients with postoperative paresis, 32 (63%) prolonged paresis were allowed conservatively, which avoided unnecessary repeated surgical interventions. In 19 (37%), the causes of postoperative complications were diagnosed and relaparotomy was performed in a timely manner to these patients. Postoperative mortality was 5.1%.