A histological study was conducted on unoperated specimens from six infants with esophageal atresia and tracheo-esophageal fistula. Sub-serial sections of the distal segment showed tracheobronchial elements in five cases, including cartilage in three. Normal esophageal layering was seen at a variable distance from the tracheobronchial end of the fistula. Tracheobronchial elements, including cartilage, were also seen in two other surgical specimens, which suggests that tracheobronchial elements may be very common in tracheo-esophageal fistula, and in some cases may lead to stenosis or abnormal motility following otherwise successful anastomosis.