Gastroduodenal intussusception is an extremely uncommon condition caused by the prolapse of a gastric tumor into the duodenum, with the subsequent invagination of a portion of the stomach wall. The lead point of the intussusception is usually a benign gastric tumor, with only a small number attributed to gastric carcinomas. Both gastroduodenal intussusception itself and a gastric carcinoma as the lead point are extremely rare. The authors present a case of gastroduodenal intussusception caused by a Borrmann type I gastric carcinoma. This case can be classified as a partial lateral invagination with a grade II internal mechanism.