It remains unknown whether oxldl and its receptor-Lox-1 mediates the anti-atherogenic action of exercise and whether HO-1 is involved in it In order to test this point 8-week-old apolipoprotein E-knockout mice (ApoE', n=30) were fed "western diet" for 12 week to establish atherosclerotic model, C57 used as homologous mice They were randomly assigned to C57 sedentary group (CC group), ApoE' sedentary group (AC group), ApoE' exercise group (AE group) Mice in exercise groups ran on a treadmill at speed from 10m/min X 30 minutes up to 13m/min X 60 minutes gradually for 5 days/wk for a total 12 weeks At the end of experiments, the atherosclerotic lesion was investigated by use of oil red "O" staining and hematoxylin and eosin (HE) staining The arterial oxld levels were investigated by ELISA analysis The immunohistochemical analysis of HO-1 and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of Lox-1 in aorta were made using computerized image analysis system The results were as follow a 12-week training program reduced atherosclerotic lesions and retarded the progression of atherosclerosis Chronic exercise decreased arterial oxidative stress including oxldl levels and Lox-1 expression Meanwhile exercise decreased the expression of HO-1 m thoracic aorta These results suggest that the anti-atherogenic action of exercise may partially attribute to its anti-oxidant activity by reducing arterial oxidant element such as the level oxldl and Lox-1 of aorta