Patent omphalomesenteric duct (umbilical enteric fistula) was diagnosed in a 7-day-old infant. The duct closed spontaneously, but at the age of 4 months the infant was readmitted for a resection of the duct. A review of the literature disclosed that 65 cases of patent omphalomesenteric duct have been reported in Japan. The male/female ratio was 2.8:1. Ten out of 36 infants (27.8%) were premature. Surgery was performed in as many patients as possible--55 out of 59 cases (93.2%). The ducts averaged 3.8 cm in length and 1.1 cm in diameter. Errant gastric mucosa was found in 3 out of 30 cases (10.0%). Prolapse of the ileum was present in 28 out of 53 patients (52.8%)--a relatively high incidence. Ten out of 55 patients died (18.2%); 8 of these had a prolapse of the ileum. In view of the high mortality rate of patients with a prolapse of the ileum and the strong possibility of intestinal obstruction, patent omphalomesenteric ducts should be resected surgically.