Idiopathic intestinal invagination is a relatively frequent process in children in comparison with cases of intestinal obstruction/subocclusion by invagination secondary to a tumor in adults which is unusual and more often observed in patients over the age of 60 years. Two clinical cases of intestinal obstruction in young adult males due to intestinal invagination by a tumor of the small intestine are presented. One case was due to a submucosal lipoma which lead to ileo-ileal intussusception and an ileo-cecal invagination by a terminal ileum lymphoma. The clinical and diagnostic aspects of this infrequent disease are discussed.