Both cellular cholesterol metabolism imbalance and apoptosis are related to the development of atherosclerosis. To investigate the relationship between the cellular cholesterol metabolism and apoptosis, the porcine aortic smooth muscle cells were cultured with medium 199 containing 15 mg/L oxidized low density lipoprotein (Ox-LDL) for 72 h, the ratio of cellular cholesteryl ester to total cholesterol increased from 26.2% to 64.1%, and Ox-LDL induced accumulation of cellular cholesteryl ester in a concentration dependent manner in the cells. It indicated that the vascular smooth muscle cells had transformed to foam cells. In addition, cells incubated with oxidized low density lipoprotein had characteristic of apoptosis, as determined by fluorescence microscope, laser scanning confocal microscope and flow cytometry. From this findings, it was speculated that the induction of apoptosis may be related to the raise of the ratio of cellular cholesteryl ester to total cholesterol besides oxidation of low density lipoprotein in vascular smooth muscle cells.