Objective To observe the relationship between ambulatory arterial stiffness index(AASI) and estimated glomerular filtration rate(eGFR) in elderly patients with essential hypertension, and to explore the roles of arterial stiffness expressed by AASI in evaluating renal function decline in elderly patients with essential hypertension. Methods Totally 218 elderly hypertensive patients with normal serum creatinine level who underwent 24 hours ambulatory blood pressure monitoring were divided into two groups according to AASI (≤0.55 or ＞0.55). The eGFR values were compared between the two groups. The correlations of eGFR with AASI, age, average systolic blood pressure, average diastolic blood pressure and serum creatinine were determined by Pearson correlation and multiple linear regression analysis. Results Compared with AASI≤0.55 group, the eGFR level was significantly decreased in AASI＞0.55 group( P＜0.001). Pearson correlation analysis showed that eGFR was negatively correlated with AASI（r=－0.624, P＜0.001）. After adjustment for age, average systolic blood pressure, average diastolic blood pressure, serum creatinine, there was still correlation between eGFR and AASI (r=－0.343, P＜0.001). Stepwise multiple regression analysis showed that eGFR values were independently associated with serum creatinine levels and AASI (standard partial regression coefficient: －0.770,－0.240, P＜0.001). Conclusion The eGFR is negatively correlated with AASI and the increase of AASI is one independent risk factor of renal function decline in elderly patients with essential hypertension.