A hundred and nine cases of cecovesical fistula are described in the literature. Although its origin is usually reported to be appendicitis, we present a rare case of cecovesical and rectovesical fistulas secondary to mucinous adenocarcinoma of the cecum. An 84-year-old man was referred to our hospital with the chief complaints of fever and cloudy urine. An enterovesical fistula was seen on cystography, and cystoscopy showed a lot of mucinous fluid in the bladder and the papillary tumor arising from the enteric mucosa was identified through the fistula. Transurethral biopsy of the tumor revealed a mucinous adenocarcinoma of suspected colonic origin. At the operation, cecovesical and rectovesical fistulas secondary to cecal tumor were removed by right hemicolectomy, low anterior resection of the rectum and partial cystectomy.