Intestinal intussusception in the adult is a rare entity that differs greatly in etiology from its pediatric counterpart. Controversy remains regarding the optimal management of this problem in the adult patient. The purpose of this study was to determine the cause(s) of intussusception and to determine the role of intestinal reduction in the management of intussusception in adults. A retrospective review performed at The Mount Sinai Medical Center identified 27 patients, 16 years and older, with a diagnosis of intestinal intussusception. Data related to presentation, diagnosis, treatment, and pathology were analyzed. There were 13 males and 14 females. The median age of the group was 52 years with a range of 16 to 90 years. Abdominal pain was the most common presenting complaint. A preoperative diagnosis was suspected in 11 of 27 patients (40%). There were 22 small bowel lesions and 5 colonic lesions. A pathologic cause was identified in 85% of patients with 8 of 22 (36%) small bowel and 4 of 5 (80%) of large bowel lesions being malignant. All small bowel cancers represented metastatic disease and all large bowel malignancies were primary adenocarcinomas. The median age of patients with malignant disease was 60 years; it was 44 years for those with benign disease. Operative treatment consisted of resection alone in 58% of patients and resection after reduction in 42%. Three patients were treated nonoperatively. Our data support a selective approach to the operative treatment of intussusception in adults. Colonic lesions should not be reduced before resection because they most likely represent a primary adenocarcinoma. Small bowel intussusception should be reduced only in patients in whom a benign diagnosis has been made preoperatively or in patients in whom resection may result in short gut syndrome.