BACKGROUND Replacement conduits carry significant morbidity in long gap esophageal atresia. Surgical myotomies can lengthen the esophagus, but have not gained widespread adoption due to long-term dilatation. The aim of this study is to assess the feasibility of an emerging minimally invasive technique of submucosal endoscopic myotomy for esophageal lengthening. METHODS Bilateral submucosal lengthening endoscopic myotomies (BSLEM) were performed in three swine. Circular esophageal muscle fibers were selectively divided in a bilateral 3 cm longitudinal pattern. Ex-vivo tensile testing was performed on the BSLEM and compared with three circular myotomies, three spiral myotomies, and three controls. RESULTS BSLEM was completed in all cases with one esophageal microperforation. The mean operating time was 38 minutes. Over physiologic force ranges of 0 to 100 g, the percentage esophageal elongation was significantly different among the four groups (p<0.05). Spiral myotomy enabled the maximal lengthening among the techniques. BSLEM enabled lengthening significantly greater than controls, but less than both types of surgical myotomy. CONCLUSIONS BSELM is feasible and allows significant esophageal lengthening. Unlike surgical myotomies, BSELM enables selective division of circular fibers to potentially preserve perfusion near the anastomosis and prevent long-term dilatation. Studies are ongoing to characterize the ideal pattern of selective endoscopic myotomy and long-term effects.