Aim To investigate whether oxidized low density l ipoprotein induces apoptosis of vascular smooth muscle cells. Methods The cultured porcine aortal smooth muscle cells incubated with oxidized low density lipoprotein of 15 mg/L for 72 hours in vitro. Then the samples were analyzed by fluorescence microscope?confocal microscope system and flow cytometry. Results Apoptosis was triggered by incubated with oxidized low density lipoprotein accompanying with apparently morphological changes. Conclusion In the process of which oxid ized low density lipoprotein induced vascular smooth muscle cells apoptosis, the abnorm al metabolism of cellular cholesterol may be have relation to apoptosis.