AIM: To evaluate whether an automatically controlled cut system (endocut mode) could reduce the complication rate of endoscopic sphincterotomy (EST) and serum hyperamylasemia after EST compared to the conventional blended cut mode. METHODS: From January 2001 to October 2003, 134 patients with choledocholithiasis were assigned to either endocut mode group or conventional blended cut mode group at the time of sphincterotomy. The two groups were retrospectively compared for the complications after EST and serum amylase level before and 24 h after the procedure. RESULTS: Of the 134 patients treated, 79 were assigned to conventional blended cut mode group and 55 to endocut mode group. There was no significant difference in age, sex, and serum amylase level before EST between the two groups. Complications were found in 5 patients of the endocut mode group (9%): hyperamylasemia (5 times higher than normal) in 4 and moderate pancreatitis in 1. Complications were found in 13 patients of the conventional blended cut mode group (16%): hyperamylasemia in 12 and moderate pancreatitis in 1. Serum amylase levels were elevated in both groups 24 h after EST (P