Objective To explore the effects of different levels of exogenous testosterone on atherosclerosis，sex hormone, blood lipid and apolipoprotein in castrated rabbits. Methods Thirty-five male New Zealand white rabbits were randomly divided into sham operation group, placebo group, hypotestosteronemia group(3 mg/kg), physitestosteronemia group(6 mg/kg), hypertestosteronemia group(12 mg/kg), with 7 in each group. Total testosterone (TT), estradiol (E2), dehydroepian?drosterone(DHEA) lipids, total cholesterol(TC), high density lipoprotein cholesterol(HDL-C), low density lipoprotein cholesterol(LDL-C), triglyceride(TG), apolipoprotein A1(ApoA1), and apolipoprotein B(ApoB) were tested at 1 week before operation and 16 weeks after operation respectively. Atherosclerosis index(AI) was obtained(AI=(TC－HDL-C/HDL-C). After 16 weeks, the aorta was observed morphometrically and immunohistologically, and the aortic cholesterol content was examined. Results Average serum lipids, atherogenic lipoproteins and apolipoproteins were significantly higher in placebo group, hypoteststeronemia and hypertestosteronemia groups than in sham operation group and physitestosteronemia group(P＜0.01). The aortic cholesterol content was (75.8±5.9), (76.3±6.1) and (75.2±2.3)mmol/g protein respectively in placebo group, hypoteststeronemia group and hypertestosteronemia group, with no significant difference between the three groups (P＞0.05), which was 2.5 times of that of physitestosteronemia group[(21.0±5.6)mmol/g protein]. The aortic cholesterol content was (21.0±5.6) and (30.9±8.4) mmol/g respectively in physitestosteronemia group and sham operation group(P＜0.01). The ratio of intima/tunica media was (0.65±0.21), (0.62±0.24) and (0.65±0.25) respectively in placebo group, hypoteststeronemia group and hypertestosteronemia group respectively, with no significant difference between the groups(P＞0.05), which was higher obviously than that in sham operation group [(0.31±0.07), P＜0.01]. It was the lowest in physitestosteronemia group (0.26±0.08), which was significantly lower than that in sham operation group(P＜0.01). Conclusions Exogenous testosterone, only at physiological level, has beneficial effects on serum lipids, lipoproteins, apolipoproteins and atherosclerosis in castrated male rabbits.