A case of primary adenocarcinoma of the vermiform appendix coexisting with transitional cell carcinoma (TCC) of the bladder is presented. The patient was a 74-year-old male who underwent radical cystectomy with continent urinary diversion using the Florida pouch. Two different cancers were found, TCC of the bladder and mucinous adenocarcinoma of the appendix. To our knowledge, this is the only such case reported in the medical literature.