Aim To study the relation between vascular angiotensin converting enzyme (ACE) activity and intimal hyperplasia in rabbit restenotic model and the effects of different doses of benazepril.Methods Angioplasty was performed in the left artery of 28 New Zealand white rabbits. Benazepril was administrated to treatment groups in lowdose(n=9,1mg/kg) and high-dose (n= 9, 10 mg/kg)respectively. All animals were sacrificed 2 weeks after angioplasty. The vascular morphometry included intimal and medial areas,thus ratio of intimal area to medial area. Serum and vascular ACE activities were determined by fluorimetric assay.Results The vascular ACE activity of angioplasty subgroup was 2. 7 times higher than that of the nonangioplasty subgroup (p<0.01). The high-dose benazepril significantly reduced the vascular ACE activity and intimal area, compared with angioplasty subgroup (p<0.01). But the low-dose benazepril only moderately inhibited the vascular ACE activity (24% down,p<0.05), and the intimal area did not alter significantly. The significant positive correlation was displayed between vascular ACE activity and intimal area (r=0.708, p<0.01).Conclusion The excessive expression of vascular ACE may play a pontential role in restenosis. The high-dose benazepril could inhibited intimal hyperplasia by suppressing vascular tissue ACE.