Objective:To evaluate the complication-based learning curve and identify learning-Associated complications of robotic gastrectomy.Summary Background Data:With the increased popularity of robotic surgery, a sound understanding of the learning curve in the surgical outcome of robotic surgery has taken on great importance. However, a multicenter prospective study analyzing learning-Associated morbidity has never been conducted in robotic gastrectomy.Methods:Data on 502 robotic gastrectomy cases were prospectively collected from 5 surgeons. Risk-Adjusted cumulative sum analysis was applied to visualize the learning curve of robotic gastrectomy on operation time and complications.Results:Twenty-five cases, on average, were needed to overcome complications and operation time-learning curve sufficiently to gain proficiency in 3 surgeons. An additional 23 cases were needed to cross the transitional phase to progress from proficiency to mastery. The moderate complication rate (CD ≥ grade II) was 20% in phase 1 (cases 1-25), 10% in phase 2 (cases 26-65), 26.1% in phase 3 (cases 66-88), and 6.4% in phase 4 (cases 89-125) (P < 0.001). Among diverse complications, CD ≥ grade II intra-Abdominal bleeding (P < 0.001) and abdominal pain (P = 0.01) were identified as major learning-Associated morbidities of robotic gastrectomy. Previous experience on laparoscopic surgery and mode of training influenced progression in the learning curve.Conclusions:This is the first study suggesting that technical immaturity substantially affects the surgical outcomes of robotic gastrectomy and that robotic gastrectomy is a complex procedure with a significant learning curve that has implications for physician training and credentialing.