Urachal disease, a disorder where embryonic remnant of the cloaca and the allantois present after birth as a midline fibrous cord, is usually detected in infancy and childhood. But urachal disease in adults is rare. We report a case of a huge abscess derived from a urachal cyst in an adult. A 52-year-old man presented with peri-umbilical distension and abdominal pain for 2 weeks. Ultrasonography and abdominal computed tomography scan demonstrated a huge abscess derived from the abdominal wall. After prompt incision and drainage, the remaining abscess cavity was removed completely under general anesthesia. Pathologic report was consistent with urachal duct cyst, and the patient was discharged in a week without complication.