Because of the high mortality rate associated with reconstruction of the esophagus by transplanting stomach or colon into the chest, simpler means of restoring continuity after esophageal resection are needed. However, if a simple anastomosis or joining of the two ends is attempted after more than 2 or 3 centimeters of the esophagus are excised, the anastomosis fails because of tension. In preliminary experiments performed by us in dogs, when end-to-end anastomosis was attempted after excision of more than 33% of the esophagus, 4 of 7 dogs died of anastomotic breakdown. In experiments performed during the current year, circumferential transection of the longitudinal muscle fibers of the esophagus (circular myotomy) resulted in relaxation of tension and allowed successful anastomosis in a majority of dogs even when 60% of the esophagus was excised. Before applying this procedure clinically, it is appropriate that it be tested in an animal whose anatomy and physiology more closely resembles that of man. Therefore, for the coming year we plan to conduct the same types of experiments in rhesus monkeys as those performed in dogs during the current year. BIBLIOGRAPHIC REFERENCES: Hankins, J.R., and McLaughlin, J.S.: Pericarditis with Effusion Complicating Esophageal Perforation. The Journal of Thoracic and Cardiovascular Surgery 73:225, 1977. Ayella, R.J., Hankins, J.R., Turney, S.Z. and Cowley, R.A.: Ruptured Thoracic Aorta due to Blunt Trauma. The Journal of Trauma 17: (March) 1977.