Abstract:Abstract: Objective?To explore the learning curve of endoscopic thyroidectomy via breast approach and summarize the experience of chief surgeon who had never performed any endoscopic surgery before.?Methods?A retrospective analysis was made on the base of 51 cases of endoscopic thyroidectomy via breast approach, which were performed by the same group of surgeons from July 2014 to March 2019. All of the cases were divided into five groups: A, B, C, D and E according to the sequence. Statistical indicators include general indicators and surgical related ones. Learning curve was analyzed by moving average method.?Results?The operation time of group A was significantly different from that of group B, C, D and E, but there were no differences among groups of B, C, D and E. There were 6 cases of surgical injuries, 3 cases of which occurred in group A. The learning curve was made according to the operation time. The results indicated that only one surgeon completed 10 cases of endoscopic thyroidectomy independently could he enter a stable stage.?Conclusion?In order to get through the learning curve and enter a stable period, a chief physician, who has never performed any endoscopic surgery, needs to complete 10 cases of endoscopic thyroidectomy via breast approach. If modified video-assisted thyroidectomy was included, the learning curve was at least 21 cases.