We report a 16 year old boy with suspected appendicitis. Besides leucocytosis a roll was palpable in the right lower quadrant. The enema with water soluble contrast medium revealed an invagination. Intraoperatively, reduction was possible. The cause was an inverted Meckel's diverticulum. In this diverticulum we found a large perpendicular hyperplasiogenic gastric polyp as the cause of inversion and invagination.