Abstract: Objective To explore the association of the levels of angiogenic T(T_ang) cells and immunologic senescence, pro-inflammatory capacity of these cells with endothelial dysfunction and systemic inflammation in hypertensive patients. Methods A total of 120 untreated inpatients with essential hypertension from the Department of Hypertension and Vascular Disease in the First Affiliated Hospital of Sun Yat-sen University were enrolled from September 2019 to March 2020. Flow-mediated dilation（FMD） of brachial artery was used to evaluate endothelial function. Based on FMD≤7% and ＞7%, patients were divided into two groups according to the presence and absence of vascular endothelial dysfunction. Proportion of CD28^null andCD28⁺ in CD4⁺/CD8⁺subset of T_ang cellsCD3⁺CD31⁺CXC chemokine receptor-4（CXCR4） ⁺ in peripheral blood and γ-interferon（IFN-γ）, tumor necrosis factor-α（TNF-α）, interleukin-6（IL-6）, interleukin-10（IL-10） positive cells, and the expression of CD57, CD27（serve as senescent profiles）, CC-chemokine receptor 7（CCR7）and human telomerase reverse transcriptase（hTERT） were measured by flow cytometry. Levels of serum cytokines including IL-6,interleukin-17（IL-17）, IFN-γ,TNF-α were detected by enzyme-linked immunosorbent assay（ELISA）. The baseline data, biochemical indicators, T_ang cells subsets, and serum inflammatory differences of two groups were compared. Pearson correlation analysis were used to analyze the correlation between the subset of CD28^null CD4⁺T_ang cells and FMD, serum cytokines. Logistic regression and receiver operating characteristic（ROC） curve were used to determine the association and diagnostic efficacy of T_ang cell subsets for endothelial dysfunction. Results The proportion of CD28^null subset was significantly higher in CD4⁺ T_ang cells in hypertensive patients with endothelial dysfunction, which was negatively correlated with FMD（r=-0.643, P＜0.01）. Multiple logistic regression analysis showed that higher proportion of CD28^nullCD4⁺T_ang cells was associated with endothelial dysfunction（OR=3.428, 95%CI 1.423-5.012, P＜0.001）, with good diagnostic performance in endothelial dysfunction area under curve（AUC）=0.885, P＜0.001. Immunophenotyping revealed that CD57 expression was increased, and CCR7, CD27, hTERT expression were decreased in CD28^nullCD4⁺T_ang cells, indicating senescence. The proportion of IL-6, IFN-γ and TNF-α positive cells were higher. CD28^nullCD4⁺T_ang cell number was significantly associated with the serum levels of IL-6, IL-17, IFN-γ and TNF-α in hypertensive patients. Conclusion Subset of T_ang cells with senescent and proinflammatory phenotype, associated with FMD and systemic inflammation, may serve as a biological marker for assessing endothelial dysfunction in hypertensive patients.