Objective：To investigate the relationship between aldosterone escape phenomena and left ventricular hypertrophy（LVH）in essential hypertension（EH） treated by angiotensin-converting enzyme inhibitor（ACEI） and angiotensinⅡ receptor inhibitor blocker（ARB）. Methods：Totally 95 cases of EH complicated with LVH were randomly divided into enalapril group（n=48） and irbesartan group（n=47）. AngiotensinⅡ（AngⅡ），aldosterone（Ald），interventricular septal thickness（IVST），left ventricular posterior wall thick－ness（PWT）and left ventricular end diastolic diameter（LVDD） levels were examined before therapy and at 1，3，6 months after thera－py. Results：（1）Levels of blood pressure were decreased in both groups and there was no significant difference between two groups（P >0.05）. （2）In enalapril group，AngⅡlevels were all decreased significantly（P <0.05） at 1，3，6 months after therapy. AngⅡlevels were slightly increased at 3，6 months after therapy compared with those at 1 month after therapy，but without statistical differences（P >0.05）. Ald levels were decreased significantly at 1 month after therapy compared with those before therapy（P <0.05） but they were increased at 3，6 months after therapy，reaching the levels before therapy（P >0.05）. In irbesartan group，AngⅡlevels were increased at 1 month after therapy compared with those before therapy，without statistical differences but they were increased at 3，6 months af－ter therapy compared with those before therapy，with statistical differences（P <0.05）. Levels of Ald were all decreased significantly at 1，3，6 months after therapy compared with those before therapy（P <0.05）. （3）IVST，PWT，LVDD levels were decreased in both groups after therapy compared with those before therapy（P ＜0.05） but there was no significance between two groups. Ald levels of some patients（19 patients in enalapril group and 2 patients in irbesar－tan group） were initially decreased but were increased after 3 months’ therapy compared with those before therapy，which was called Ald escape. LVH ameliorations of these paitents were quiet. Conclusions：Ald escape may occur in EH treated by ACEI and ARB. LVH ameliorations in these paitents with Ald escape phenomena are quiet.