Aim To investigate the effect of testosterone on intimal proliferation after rabbit abdominal aorta balloon injury. Methods 24 male New Zealand white rabbits were divided randomly into control group (n=8, sham castration), hypotestosteronemia group (n=8, castration) and testosterone replacement group (n=8, castration +testosterone undecanoate, 14 mg/kg). Abdominal aorta was not injured with 3 mm PTCA balloon until testosterone undecanoate had been injected for three days. After injury two weeks later, blood samples were obtained for detection of plasma testosterone, nitric oxide (NO), superoxide dismutase (SOD) and malondialdehyde (MDA), and all the abdominal aortas were excised to be analyzed by computer. Results The intimal area and PCNA proliferation index of control group and testosterone replacement group were significantly decreased than those of hypotestosteronemia group (P<0.01), together with a significant increase in NO plasma level and significant decrease in MDA plasma level. No difference was observed between control group and testosterone replacement group in all parameters. Conclusions Testosterone, at physiological level, inhibits the intimal proliferation induced by balloon injury in male rabbit abdominal aorta. It might be related to increasing the synthesis of NO and the effect antioxidation.