Aim. To identify the specific features of modifying the lipid composition of the red blood cell membrane in people with isolated hypercholesterolemia without coronary heart disease (CHD) and in CHD patients with different functional classes of angina pectoris. Subjects and methods. 92 men with Functional Class II—IV stable angina, 22 men with isolated hypercholesterolemia (HC) without CHD, and 18 healthy men with normal cholesterol levels were examined. Blood plasma cholesterol levels were determined in all the examinees. The erythrocyte membrane was examined for the levels of lipid peroxidation (LPO) products, free cholesterol, calcium, and phospholipid fractions and for the activity of Na+/K+-, Mg2+- and Ca2+-ATPases; a bicycle exercise test was carried out. Results. As compared with persons with normal blood cholesterol levels, the examinees with HC without CHD were found to have higher levels of LPO products, lower levels of readily oxidizable phospholipid fractions, decreased activity of membrane-bound Na+/K+-, Mg2+-, and Ca2+-ATPases, and elevated concentrations of free cholesterol and calcium in the red blood cell membrane. Having the pronounced activity of free radical oxidation, the patients with CHD were detected to have deeper similar structural changes in the cell membrane, which became more severe with a larger number of affected coronary arteries. Conclusion. The findings suggest that the lipid structure of the cell membrane undergoes changes associated with its functional depression just at the preclinical stage of atherogenesis. Biomembrane structural modification in patients with angina pectoris progresses in proportion to the number of affected coronary arteries, by limiting the functional reserve of the cell and whole body.