Urachal pathology is rare. The most frequently reported lesion is urachal adenocarcinoma. The pathogenesis of urachal adenocarcinoma is unknown. We report a case of a 55-year-old man who presented with microscopic hematuria. Clinical work up showed a tumor involving the urinary bladder with extravesical extension. Masses or tumors involving other organs were excluded. Partial cystectomy revealed a distended bladder wall with the formation of a cystically dilated mass filled with mucoid material. Microscopic examination showed enteric type adenocarcinoma with abundant mucin formation. The neoplastic urachal epithelium showed features of colonic differentiation as evidenced by the presence of goblet cells and positive staining for acid mucin and cytokeratins 20 (CK 20). Such features are absent in non-neoplastic urachal epithelium. This was a rare case of urachal adenocarcinoma, enteric type, with abundant mucin formation. The urachal adenocarcinoma had morphological features and an immunohistochemical profile that were similar to that of adenocarcinoma of the colon.