Rates of fraction catabolism of rabbit and horse total 125I-high density lipoproteins (HDL) were shown to be similar in rabbits, after intravenous administration, while catabolism of human, dog and, especially, of rat lipoproteins occurred at the higher rate as compared with rabbit HDL. Rabbit HDL containing modified epsilon-aminogroups, or guanidine groups, or carboxyl groups and native HDL were quite similarly eliminated from circulation of healthy animals, whereas the lipoproteins with modified tyrosine residues and, especially, succinated HDL exhibited the highest rate of elimination. Radioactivity of spleen tissue and lymphatic glands was several-fold higher after intravenous administration of succinated homologous 125I-HDL into rabbits as compared with the effect of native homologous 125I-HDL; in kidney, adrenal glands, liver tissue and small intestine the level of radioactivity was analogous after treatment with both homologous native and succinated 125I-HDL. During incubation with mice peritoneal macrophages modified lipoproteins were captured 1.5-fold more effectively as compared with native HDL. The data obtained suggest that the type of HDL catabolism prevailed in rabbits, which did not involve specific cell receptors to apoprotein components of these lipoproteins.