Contractile cardiomyocytes in various parts of the heart differ in shape, size, ploidy, and other parameters. However, it is not known whether their population is heterogeneous within each heart chamber. In this paper, dry weight and ploidy of cardiomyocytes were estimated in different parts of rat left ventricle. It was found that the dry weight of cardiomyocytes in medial part of left ventricular anterior wall is higher than in other parts of the ventricle. Cardiomyocyte ploidy is the same in different regions of the left ventricle.