Introduction: Omphalo-mesenteric fistula is a rare form of the regression anomaly of the omphalo-mesenteric duct. The diagnosis is usually clinical, confirmed by simple fistulography in case of doubt. In rare cases, complications (occlusion, infection, ulcer, prolapse) may be revealing. Observation: We report an omphalomesenteric fistula revealed by prolapse in a three-day-old newborn. The diagnosis was obvious by the outcome of stool through the prolapse orifice. Treatment consisted of bowel resection on either side of the omphalo-mesenteric canal followed by terminal anastomosis. Conclusion: Omphalomesenteric fistula, often revealed as a complication, becomes an emergency and surgical treatment is quickly required