A case of congenital patent urachus is reported. A 12-month-old boy was referred to our outpatient clinic with the complaint of watery discharge from the navel. A cystography revealed the communication between the dome of the urinary bladder and the umbilicus. Excretion from the umbilicus of indigocarmine solution instilled into the urinary bladder was recognized. There were no complicated abnormalities in other organs. The patient underwent radical operation. Herein, we collected 164 cases of urachal disorders reported in Japan and reviewed the incidence, clinical symptoms, diagnosis and treatment. The classifications of the disease were briefly discussed.