Appendiceal intussusception is a very rare pathological condition, an incidence, as revealed by appendectomy specimens, of only 0.01 percent. There are various types among which complete invagination of the appendix is very rare. We encountered a case of intussusception of the appendix with complete invagination induced by appendiceal adenocarcinoma. A preoperative diagnosis of appendiceal adenocarcinoma and intussusception was not possible, but a final pathological report confirmed these conditions and retrospective analysis of a barium enema showed a finger-like filling defect of the cecum, a relatively specific finding in such cases. We describe a case involving a 39-year old man who one month earlier had noted the onset of pain in the right lower abdomen.