Congenital tracheo-oesophageal fistula without atresia can persist and remain undetected until adulthood. We present such a case and give a review of the literature. Symptoms are commonly present during infancy, but to confirm diagnosis of a fistula is often exceedingly difficult. We visualized the fistula in our case by means of a bronchofibrescope when all the other available tests had failed. The speculations as to how these patients reach adult life have been many, but we consider that we have found an important and hitherto undescribed answer to this question, namely a sphincter mechanism in the fistula.