A 48-year-old woman was admitted to our hospital with the complaint of right lower abdominal pain. On admission, the physical examination revealed tenderness, muscle guarding and rebound tenderness in the right lower part of the quadrant. Although ultrasonography and computed tomography showed a right ovarian cyst, a diagnosis of panperitonitis due to appendicitis was made. An emergency operation was performed. At laparotomy, a great deal of ascitic fluid and a ruptured right ovarian cyst measuring about 5 cm in diameter were found. She was diagnosed as having panperitonitis due to a ruptured right ovarian cyst. Moreover, exploration of the cecum showed a tumor surrounded by a hard adhesion. The appendix could not be found. It was suspected that the tumor was a malignant neoplasm of the cecum and right hemicolectomy with right oophorocystectomy was performed. This case was diagnosed as appendiceal intussusception associated with endometriosis by pathological findings. The overall incidence of intussusception and endometriosis of the appendix is estimated as 0.01% and 0.05%, respectively. According to the literature, only 3 cases of appendiceal intussusception associated with endometriosis including ours have been reported in Japan. As histopathological diagnosis was difficult to obtain prior to the resection, meticulously planned treatment strategies are called.