Objective To investigate the short- and long-term complications after endoscopic Oddi's sphincterotomy (EST) upon endoscopic retrograde cholangiopancreatography (ERCP) procedure and determine whether the size of EST correlates to the occurrence of EST complications.Methods 95 cases receiving EST in the process of ERCP in our hospital were studied and followed up. The patients were divided into large, moderate and small incision groups according to the size of EST and the states of short-term and long-term EST complications were statistically analyzed.Results The incidence of short-term complications of EST was 18. 94% (18/95). They included bleeding in the process of ERCP in 11 cases, delayed bleeding in 3, acute pancreatitis in 1, acute cholangitis in 2 and duodenal perforation in 1. All these patients but 1 with duodenal perforation were discharged after undergoing symptomatic treatments. Eleven out of the 95 patients had long-term complications (11.57 % ). These included biliary system infection in 5 cases, recurrent calculus of bile duct in 3, papilla stricture in 1 and chronic relapsing pancreatitis in 2. All 11 patients recovered after therapeutic ERCP again or symptomatic drug treatments. There was no significant difference in incidence of short-term (χ2 =2.433, P=0.296) or long-term complications (χ2 = 1.151, P=0.562) among the 3 groups. Furthermore, there was no statistical correlation between the incision size of Oddi and complications including operative bleeding (P=0.109), short-term complications (P=0.124) and longterm complications(P=0.402). Conclusion There are many short-term and long-term complications after EST, but there is no correlation between the complications and the incision size of Oddi. The occurring rate of complications might be reduced through accurate direction of papilla incision, avoidance from injury of blood vessel, keeping bile drainage unobstructed and protection of the function of Oddi sphincter as far as possible in the process of ERCP.