Intussusceptions in adults are relatively rare. About 70% to 90% of cases have demonstrable etiologies, and 40% of them are caused by malignant neoplasm. Diagnosis may be difficult with conventional diagnostic techniques due to the low incidence and the rare consideration to intussusception in adults. Computed tomography (CT) is now widely used in the evaluation of abdominal mass and nonspecific abdominal pain that may be the first presentation of an intussusception. But, CT is often not successful in determining the specific causes of the intussusception, as the lead point in many cases is small and often hidden within the intussuscepted mass. We report two cases of adult intussusceptions by sigmoid colon cancer with three-dimensional reconstruction of conventional CT. (Intestinal Research 2006;4:69-73)