Adenocarcinoma of the vermiform appendix is a rare disease that constitutes less than 0.5% of all gastrointestinal malignancies. A patient was admitted with abdominal discomfort and urinary frequency but no symptoms suggestive of enterovesical fistula, e.g. pneumaturia or urinary tract infection. She was diagnosed with adenocarcinoma of the appendix with a fistula to the urinary bladder.