2019 © University of Ankara. All Rights Reserved.Objective: Cardiovascular complications are the leading causes of mortality and morbidity in diabetic patients. Hypergylcemia plays the major role in the pathogenesis of these complications. On the other hand, dietary polyphenols are known to have preventive effects on the development of cardiac diseases.Tea consumption, which is known to be a rich source of polyphenols, has been shown to decrease incidence of cardiac diseases and cardiovascular mortality. Epigallocatechin gallate (EGCG) is the major polyphenolic substance found in tea. EGCG is known to have protective effects in cardiac pathologies such as diyabetes. Nevertheless, to our knowledge, their direct cardiac effect at the cellular level is not known. Thus, we aimed to investigate its effects under normal (5,5 mM) and high glucose (25,5 mM) concentrations. Material and Method: Wtih this purpose, freshly isolated ventricular cardiomyocytes were incubated with high glucose for 3 hours. EGCG was added 30 min prior to high glucose to a group of cells. A video-based edge detection system (IonOptix) was used to record changes in cell length during cell shortening and relengthening. Result and Discussion: EGCG decreased hypertrophic response of hyperglycemia. However, it decreases contractility under both normal and high glucose concentrations. To understand the detailed mechanism of its negative inotropic effect, further investigation is needed.