We report herein a case of idiopathic intussuception in adults. A 70-year-old female was admitted toour hospital because of severe abdominal pain. Abdominal CT scan and echography yielded images of anintussuscepted intestine and enabled us to make a diagnosis of intussusception of the terminal ileum. Laparotomy revealed 20 cm of terminal ileum intussusception distal to Bauhin's valve. Since about 10 cm of the ileum already showed a severe ischemic change, we resected the ileocecum. During the operation, we discovered an anatomical abnormality : the ascending colon was not fixed to the retroperitoneum. However, no organic abnormalities that might have induced the intussusception were detected.