The authors describe the case of a 86-year-old female patient admitted to hospital with acute abdomen of the inflammatory type. The condition developed in the course of cca three days with sudden deterioration on the day of admission to hospital. Contrast X-ray examination revealed perforation of the distended jejunum and surgery revealed diffuse peritonitis the source of which was the mentioned perforation associated with mechanical ileus caused by malrotation and adhesions of the small intestine. An additional finding which, however, dominated on X-ray examination of the gastrointestinal tract when using contrast material and on revision of the peritoneal cavity was multiple diverticulosis of the small intestine. The uncommon finding on the small intestine and the relatively sparse data in the literature on diverticulosis of the jejunum and ileum made us submit the case-history for publication.