Three newborns with congenital tracheoesophageal fistula were treated by endoscopic laser coagulation. After radiologic and endoscopic diagnosis, laser coagulation of the mucosal layer of the fistula followed using Nd:YAG laser light transferred through an uncovered quartz fiber of 600 microns diameter. The successful and uneventful course in two cases contrasts with the incomplete obliteration in one case caused by inadequate energy application and/or early localized instillation of contrast medium for radiologic control examination. The advantages of this method include elimination of an operative procedure, exclusion of operative complications, and the possibility of repetition in recurrent cases. Care must be taken to prevent esophageal and tracheal damage by use of this method.