['We assessed the hypothesis whether behavioral stress may affect the development of atherosclerosis and whether regular exercise training may influence the composition of atherosclerotic plaques in apolipoprotein (apo) E-deficient mice.', 'Atherosclerosis was induced in apo E-deficient mice fed a high fat diet. Exercise training (45 min swimming, 3 times/week) was conducted, and behavioral stress was provoked by glass marble-burying procedure. Mice were treated with marble-burying, marble-burying behavior plus swimming training, and swimming alone over 8 weeks.', 'Exercise training decreased the atherosclerotic lesions, but marble-burying behavior increased the lesions. The plaques containing macrophage accumulation with intercellular adhesion molecule-1 (ICAM-1) expression associated with reduced collagen contents were induced in the mice treated with marble-burying. However, ICAM-1 expression was suppressed and collagen contents were reversed in the mice that received marble-burying behavior plus exercise training. In addition, exercise alone and concomitant exercise training reduced the superoxide production in aortic walls, shown by dihydroethidium staining, compared with that in mice with marble-burying behavior alone. There were no significant differences in the serum lipids profiles among the groups.'] Are atherosclerotic plaques induced by marble-burying behavior stabilized by exercise training in experimental atherosclerosis?