Abstract： Objective To study if tumor retraction assessed by endiscopic uhrasonography (EUS) during radiotherapy has prognostic value in esophageal carcinoma, which may further predict the radiosensi-tivity. Methods The maximal tumor thickness was measured by EUS before radiotherapy and at 40 Gy in patients with esophaged carcinoma. Response was defined as at least 50% reduction in tumor thickness. Re-suits A total of 51 patients were included. The median follow-up time was 28.5 months. The median sur-vival time was 24.3 months. The treatment was radiotherapy alone, concurrent chemoradiotherapy and pre-operative treatment in 35, 10 and 6 patients, respectively. Tumor response was assessed by EUS in 18 pa-tients (34%). The 2-year overall survival (OS) and progression-free survival (PFS) were 69% and 59% for responders, comparing with 37% and 29% for non-responders (χ~2= 5.78, P = 0.016 and χ~2= 3.97, P =0.046, respectively). In radiotherapy alone group, the 2-year OS and PFS were significantly higher in responders (n = 11) comparing with non-responders (n =24)(60% vs 44% ,χ~2 =5.84,P =0.016 and 20% vs 10% ,χ~2 =4.20, P =0. 040). In preoperative radio (chemo) therapy group (n =6), pathological-ly complete response, partial response and minimal response were observed in 4, 1 and 1 patients, respec-tively. EUS detected tumor response in 4 of 5 (80%) patients with tumor regression, and non-response in 1 of 1 patient without tumor regression. Conclusions The prognosis is better in patients with esophageal car-cinoma responding to neoadjuvant treatment identified by EUS than that of non-responders.