The lipoprotein composition and apoprotein composition of the major lipoprotein fraction (high density lipoprotein) were compared in White Carneau and Show Racer plasma. The capacity of the plasma and lipoproteins to activate the triacylglycerol hydrolyzing activity of lipoprotein lipase in vitro was compared in the two strains of birds and found to be identical in each case. It appears unlikely that differences in lipoprotein composition or tissue lipoprotein lipase activity will be reflected in the flux rates of lipoproteins in the two strains which have different susceptibilities to atherosclerosis.