Aim To determine the influence of exogenous testosterone on early atherosclerosis in cholesterol-fed male Wistar rats and its possible mechanisms. Methods Thirty-six male Wistar rats were randomly assigned to the three groups: normal group, cholesterol group, treated group (testosterone cypionate,2.5 mg/kg, im.); plasma lipids and the lipids content of aorta and liver were analyzed with enzymatic methods after twelve weeks, aortic intima were examined with light microscope. Results Plasma lipids and lipoproteins were not significantly different between cholesterol group and treated group, the treated rats had significantly higher plasma lipid oxidative peroxidation products value, lower hepatic lipids contents, but higher aortic lipids contents than the cholesterol group, the number of monocytes adhering to endothelial cells and oil red O positive foam cells was more in the treated group than the cholesterol group. Conclusion Exogenous testosterone accelerated early atherosclerosis in male hypercholesterolemic rats.