Urachus’ carcinoma represents a rare oncologic disease with an unfavourable prognosis due to the usual delay of correct diagnosis for its anatomical localization. Its surgical treatment varies from radical cystectomy to segmentary resection of the bladder with pelvic lymphadenectomy. We report a case occurred in a ninety years old female, in which the diagnosis was achieved only at laparotomy. The patient was submitted to surgery with the only generic diagnosis of “lower abdominal mass”, and treated with segmentary resection.