A 73 year-old woman who was treated for breast cancer and visited our hospital regularly was suspected of having a mucinous cystadenoma of the appendix. Malignancy could not be determined using abdominal computed tomography, magnetic resonance imaging, or colonoscopy. Even if mucinous cystadenoma is benign, there is the possibility that the tumor will rupture, discharge its contents, and cause pseudomyxoma peritonei. We performed laparoscopic appendectomy. According to the histopathological results, the tumor was diagnosed as a low grade appendiceal mucinous neoplasm. We report a case of mucinous cystadenoma of the appendix treated using laparoscopy-assisted appendectomy and discuss the case with literature reviews.