Abstract: AimTo observe the regression effect of tetrandrine (Tet) and enalapril (Ena) on vascular morphological changes in renovascular hypertensive (RH) rats. MethodsRenovascular hypertension was induced by two kidney one clip (2K1C) operation. The morphometric measurements were performed in the aorta, caudal artery, renal arterioles, coronary arterioles and mesenteric arterioles. ResultsThe wet weight of aorta, caudal artery and femoral artery of RH rats (18 weeks after 2K1C operation) were greater than those of sham-operated rats. The media thickness, lumen diameter, cross section of media, media over lumen ratio and the wet weight of abdomen aorta, caudal artery, coronary arterioles, renal arterioles and mesenteric arterioles were significantly increased, which were more significant in arterioles with the diameter smaller than 70 μm. There were no significant change in the number of the smooth muscle cells (VSMC) in most vessel wall, except in renal arterioles, where the number of smooth muscle cells were significantly increased. After Tet (50 mg·kg^-1·d^-1, po) or Ena (6 mg·kg^-1·d^-1, po) treated for 9 weeks from week 9 after 2K1C operation, almost all the changes in the media thickness, the media to lumen ratio, the cross section of media and the wet weight were ameliorated. ConclusionIn RH rats, mainly a hypertrophic and rearrangement remodeling in the wall of arteries and arterioles was observed with a proliferation of VSMC in renal arterioles. Tet and Ena were shown to regress vascular remodeling by markedly attenuating these changes in renovascular hypertensive rats.