Congenital tracheoesophageal fistula associated with carcinoma of the lung in an adult. A rare case of adult congenital H-type tracheoesophageal fistula was diagnosed. Subsequently, at operation, large cell, undifferentiated carcinoma of the right middle lobe with extension to the right lobe and adherence to the diaphragm was documented. The diagnosis, surgical intervention, and 4-year follow-up are presented. 