After 2 years of mucusuria a villous adenoma of the urachus was resected from a woman by partial cystectomy and excision of the entire urachus. Convalescence was uneventful and the patient was well 12 months later. Urachal adenomas are rare, this being the sixteenth case reported. Generally, they are multilocular cystic tumors lined by columnar epithelium with a population of mucous goblet cells. Often, there is a striking resemblance to gut epithelium. Ultrastructurally, by transmission and scanning electron microscopy, the tissue resembles gut mucosa. Urinary mucus is a common and relatively specific symptom for adenomas of the lower urachus, occurring in 7 of 11 cases. Resection alone is effective therapy but care must be exercised to avoid spilling adenoma cells in the peritoneum.