Hypercholesterolemia has a major contribution to the occurrence and progression of atherosclerotic lesions. Recent studies report the involvement of branched-chain amino acids in cholesterol methabolism. The aim of this research was to evaluate the role of valine, leucine and isoleucine on the occurrence and progression of atherosclerosis in rats receiving hypercholesterolic diet. Material and methods: 50 male Wistar rats distributed into five groups with the following type of diets: group I (control) received standard diet; group II - cholesterol; group III - cholesterol and valine; group IV - cholesterol and leucine; group V - cholesterol and isoleucine. The experimental study was conducted over a period of 2 months. The animals were evaluated for the serum levels of total cholesterol at the beginning of the experiment, after 1 month and after 2 months. The collected tissue fragments of heart and aorta were prepared for the examination by optical microscopy in order to identify the atherosclerotic changes. Results: The most increased values of serum cholesterol were recorded in rats from group II (p=0.001), for the second and third evaluation. The histological examination showed early histopathological lesions on the vascular intima for the groups treated with cholesterol, valine, leucine, and isoleucine. These early changes (the occurrence of some superficial endothelial erosions, adhesion of erythrocytes and platelets) were correlated with the degree of the arterial wall damage, of the leukocytes adhesion to the arterial intima, and the discontinuities of the internal elastic lamina. Conclusion: The comparative study of the effects of the three essential amino acids revealed that valine induced a faster response than leucine and isoleucine on the improvement of biochemical parameters, but there were no significant differences between the three amino acids in terms of their protective ability, demonstrated by the histopathological lesion assessment.