Endoscopy of the upper digestive tract with flexible instruments is presently a safe, widely used technique in gastrointestinal pathology. Some cases of changes in cardiac rhythm, ventricular fibrillation, ischaemia and cardiac arrest, have, however, been observed during EGDS. The incidence of arrhythmias during EGDS in 41 patients, monitored during the examination with Holter's ECG, has been observed. The results obtained confirm that EGDS does not bring noteworthy cardiovascular changes sufficient to suspend the examination. The absence of parasympathicomimetic effects makes it possible to consider thyropramide one of the drugs of choice in medication before EGDS.