We studied the phospholipid composition of high-density lipoproteins in patients with hypercholesterolemia before and after treatment with simvastatin. Individual phospholipids were separated by thin-layer chromatography on glass plates coated with silica gel. It was found that apart from hypolipidemic effect, simvastatin changed the concentration and phospholipid composition of high-density lipoproteins, which improved their cholesterol-accepting and cholesterol-transporting properties.