Background and study aims Anticholinergic premedication has not been validated for endoscopic submucosal dissection (ESD). In this randomized, double-blind, placebo-controlled trial, we investigated the efficacy and safety of glycopyrrolate as a premedication for ESD. Methods A total of 196 patients undergoing ESD at a single tertiary medical center between December 2014 and February 2016 were randomly allocated to receive one of the following two premedications: glycopyrrolate (0.004 mg/kg intramuscularly [IM]) or placebo (2.0 mL normal saline solution IM). All patients received the premedication 30 minutes prior to ESD in a double-blind manner. The endoscopists reported the ease of performing the procedure and the incidence of secretion-induced hypoxemia, cough, and other procedure-related adverse events. Results Glycopyrrolate and placebo were received by 96 and 100 patients, respectively. ESD was successfully performed in all patients without any serious adverse events related to sedation or ESD. The median visual analog scale for procedure ease was higher in the glycopyrrolate group at 8 (interquartile range [IQR] 7 - 9) vs. 7 (IQR 6 - 8.25); P < 0.001. The proportions of patients with secretion-induced hypoxemia (4.4 % vs. 14.3 %; P = 0.03) and cough (16.7 % vs. 35.7 %; P = 0.005) were lower in the glycopyrrolate group. Conclusions The use of glycopyrrolate as a premedication for ESD significantly improved the ease of performing the procedure and reduced the incidence of secretion-induced hypoxemia and cough during ESD. Glycopyrrolate may be a promising premedication to ensure safe and stable ESD procedures.