Changes in the heart rate, blood pressure, ECG, occurring at the time of endoscopy of the stomach were studied in a group of 59 cases of cardiovascular disease and in a control group of 27 cases. With regard to arrythmias appearing at the time of endoscopy of the stomach, ventricular and atrial premature beats were the most numerous. Atrial fibrillation, as well as ventricular bigeminy were encountered. Two cases of atrial fibrillation continued even after the end of the examination. ST-T changes during endoscopy were found most frequently in the ischemic heart disease group and the valvular heart disease group. There were three cases in which severe ST depression made it necessary to stop the examination. The cardiovascular changes generally occurred at the beginning of the endoscopy examination. Two milligrams of propranolol i.v. seemed to be effective in preventing changes of heart rate.