Primary mucinous adenocarcinoma is an extremely rare type of bladder cancer, with aggressive behavior and poor response to chemotherapy and radiotherapy. The symptoms are similar to those of other bladder tumors. Surgery is the main treatment and remains the only curative option. There may be a progression from mucinous metaplasia to mucinous adenoma and then mucinous adenocarcinoma. We present the case of a 40-year-old woman with recurrent lower urinary tract infections, submitted to imaging tests, which showed a bladder tumor. After transurethral resection, pathology showed intestinal mucinous carcinoma. Metastatic work-up was negative. New surgical procedure showed metaplasia but no recurrence of the carcinoma. The patient is now using antibiotic prophylaxis and will undergo a cystoscopy every 3 months and computed tomography in one year.