Appendiceal mucocele is a rare entity frequently associated with colorectal cancer. We report two cases of mucocele associated with colorectal tumours. The first case (male, 64 yrs) is an appendiceal mucinous cystadenoma found incidentally during surgery for colon cancer. There is no evidence of disease after a 4-year follow-up. The second case (male, 66 yrs) is a mucocele associated with mucosal hyperplasia that was found during surgery for acute appendicitis with a periappendicular abscess. Endoscopic follow-up showed a rectal adenocarcinoma that was initially treated with local excision with T.E.M.. Examination of the pathology specimen documented vascular invasion and the patient underwent curative colorectal resection. The preoperative radiological and endoscopic diagnostic procedures and the current therapeutic approaches described in the literature are reviewed. The relevance of the association between appendiceal mucocele and colorectal cancer is emphasized. Thorough investigation of the colorectal tract is recommended after diagnosing an appendiceal mucocele.