Aim To investigate the atherogenic role of very low density lipoprotein (VLDL) and intermediate density lipoprotein (IDL) fraction isolated from plasma of LDL receptor (LDLR)-knockout mice. Methods The lipoprotein fraction containing both VLDL and IDL fraction (LDLR ko-VLDL/IDL) was isolates from plasma of LDLR-knockout mice by ultracentrifugation. The lipid content of the fraction was determined on a Hitachi 7450 automatic analyzer, and its electrophoresis mobility and apolipoprotein components were respectively determined with agarose gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In addition, its interaction with J774 macrophages was studied. Results After LDLR ko-VLDL/IDL was incubated with J774 macrophages , the cholesterol ester (CE) content [(73±0.5) μmol/(g. cell protein)] in macrophages increased markedly, which was an 9-fold increase over the corresponding lever induced by native LDL [(8±7) μmol/(g. cell protein)] and significantly higher than non-loaded group (P<0.005). Conclusions Unmodified LDLR ko-VLDL/IDL fraction could be actively taken up by J774 macrophages and transferred the macrophages to foam cells .