Increase in activity of fatty tissue lipoprotein lipase and blood plasma post-heparin lipoprotein lipase, decrease in activity of myocardial lipoprotein lipase as well as in the rate of intracellular lipolysis of triacylglycerols in fatty tissue, unaltered activity of liver tissue endothelial lipase were observed in rabbits with moderate alimentary hypercholesterolemia (9.63 +/- 3.48 mumole of cholesterol per ml of blood plasma as compared with 1.51 +/- 0.16 mumole/ml under conditions of normal state). The ratio of stearate was increased in composition of unesterified fatty acids from blood plasma, mesenteric lymph and myocardial sarcolemma as well as in triacylglycerols of chylomicrons total fraction, in very low density lipoproteins and their remnants. Ratios free stearate/total content of other acids correlated in blood plasma and myocardial sarcolemma (r = 0.65). Any shifts in the spectra of fatty acid residues of phospholipids were not found in myocardial membranes. In rabbits with alimentary hypercholesterolemia importance of intestine-derived triacylglycerols for production of circulating unesterified fatty acids was increased, as a result of which the ratio of various acyls, metabolized in myocardium, was altered.