Objective To investigate the prophylaxes, diagnosis and treatment of pelvi-peritoneal hernia (PPH) after Miles operation for rectal carcinoma. Methods Three hundred and nine patients who underwent Miles operation from January 1986 to June 1999 were collected and analysed retrospectively, 11 of them were complicated with PPH. Results The morbidity of PPH after Miles operation was 3.6% (11/309). The main manifestations included abdominal distention to some extent (11 cases), pain (3 cases), vomiting (2 cases), gastric liquid more than 500 ml a day by gastric tube (3 cases), and non-exsufflation of the stoma of colostomy (11 cases). Two cases had pea green small intestinal liquid by perineal tube. The signs were slight abdominal tender (5 cases), active or excessive intestinal gurgling sound (7 cases), and diminished intestinal gurgling sound (4 cases). Abdominal plane films, showing the distant small intestinal obstruction, were taken in all 11 cases. Only 2 patients were correctly diagnosed before reoperation, and other patients were regarded as adhesive intestinal obstruction. The average observational time following appearance of the clinical manifestations after Miles operation was 7.4 days. All patients were diagnosed by laparotomy, 3 of them underwent adhesion lysis and reposition, and 8 patients partial ileum resection and anastomosis. The content of the hernias was ileum. The morbidity after reoperation was 27.3% (3 cases), and the complication was wound infection. All 11 patients were cured and left hospital. Conclusion The PPH after Miles operation is often lack of typical clinical manifestations. The early diagnosis and laparotomy in time is key to management. It is important to prevent the complication.