Objective:To investigate effects of estradiol(E2) on T lymphocytes in angiotensinⅡ (AngⅡ)-induced hypertrophy in mice. Methods:Eight-to 10-week-old female C57BL/6 mice suffered ovariectomy were randomly divided into experiment group (E2+AngⅡ) and control group(Placebo+AngⅡ). At the beginning,E2 sustained release tablets (0.25 mg/60 d) were implanted into the experiment group and placebos were implanted into the control group. Four weeks after E2/placebo implantation,Osmotic mini-pumps containing AngⅡ [1000 ng/(kg-min),4 weeks] were implanted subcutaneously in both groups and induced hypertrophy. During the whole experiment,blood pressure was measured at the end of 1th,2th,4th,6th,8th week. At the end of 4th and 8th week,echocardiography was performed to measure interventricular septum (IVS),left ventricular interior diameter (LVID),left ventricular posterior wall (LVPW) at diastole and calculate ejection fraction (%EF) and fractional shortening (%FS). At the same time,we analyzed immunologic markers on T cells from mice in groups by multicolor flow cytometry (Canto Ⅱ,BD). Heart morphologic changes were detected by HE staining at the end of 8th week. Results:Blood pressure in E2+AngⅡ group was lower than that in Placebo+AngⅡ group at the end of 6th,8th week (P < 0.05). IVS and LVPW were alleviated in E2+AngⅡgroup than that in Placebo+AngⅡgroup. Before giving Ang II,the fraction of total T lymphocytes,CD4+T cells,CD8+T cells and the ratio of CD4+ and CD8+ were not statistically significant. Giving AngII for 4 weeks,the fraction of circulating total T lymphocytes cells and CD8+T cells in E2+AngⅡ group were lower than that in Placebo+AngII group (P < 0.05). The fraction of circulating CD4+T cells and the ratio of CD4+ and CD8+ in E2+AngⅡ group were higher than those in Placebo+AngII group (P < 0.05). Conclusion:E2 alleviated hypertrophy induced by chronic AngⅡ. During the process of hypertrophy,E2 could decrease the fraction of total T lymphocytes cells and CD8+T cells,and increase the fraction of CD4+T cells and the ratio of CD4+ and CD8+. Our research indicated that E2 could affect T cells population to alleviated hypertrophy induced by AngⅡ.