Gastric bezoars are collection of indigestible material in the stomach, and these can be classified into five broad categories: phytobezoar, trichobezoar, pharmacobezoar, lactobezoar and miscellaneous materials such as sand, stone and concrete (gypsum). The treatment of gastric bezoars has recently changed from surgical management to such nonsurgical interventions as enzymatic dissolution, nasogastric suctioning and endoscopic removal by polypectomy snare and basket. Up to the present, electrohydraulic lithotripsy has been a well established method for the treatment of urinary and hepatobiliary stones. We report here on a patient who had a huge gastric bezoar that was formed by the ingestion of gypsum, and this was treated with endoscopic electrohydraulic lithotripsy. (Korean J Gastrointest Endosc 2005;31:328333)