ABSTRACT Background-Schistosomiasis is a trematode infestation causing a chronic granulomatous disease in various organs. Both S. mansoni & S. haematobium are endemic in Ethiopia. Most infected individuals are asymptomatic. Ectopic schistosomiasis can affect the lungs, genitalia, CNS, skin, peritoneum, Lymph nodes & other organs. Schistosomiasis as a cause of acute abdomen is seldom reported. Case Detail-A 51years -old male Ethiopian farmer presented with a two weeks history of abdominal pain with recent onset bilious vomiting and abdominal distention. Emergency laparotomy done & the finding was multiple tiny whitish nodule over the peritoneum & small bowel with multiple mesenteric lymphadenopathy. The diagnosis was confirmed with histopathology study.Conclusions- Schistosomal peritonitis is a very uncommon form of schistosomiasis. Physicians should be aware of such atypical presentation in patients from endemic areas of schistosomiasis. And biopsy should be considered in unsettled forms of peritonitis during laparotomy. The pathogenesis is not well known which warrants further study.Key words- Peritoneal schistosomiasis, acute abdomen, S. mansoni