Arterial stiffness exemplified by the ambulatory arterial stiffness index (AASI) and pulse pressure (PP) predicts cardiovascular morbidity and mortality. The present cross-sectional study assessed the association of renal function with AASI and 24-h PP in hypertensive inpatients. Subjects included 948 hypertensive inpatients with drug treatment (mean age, 53.3 years; male, 67.1%). The AASI was defined as 1 minus the regression slope of diastolic over systolic blood pressure readings obtained from 24-h recordings. Renal function was evaluated by serum creatinine and urinary albumin excretion was expressed by the urinary albumin-to-urinary creatinine ratio (ACR), and estimated glomerular filtration rate (eGFR) was calculated by the modification of diet in renal disease formula and chronic kidney disease-epidemiology collaboration formula. As AASI and 24-h PP increased, serum creatinine concentrations and ACR increased, and eGFR decreased. Multiple linear regression showed that AASI and 24-h PP were associated with eGFR-EPI (B=-12.00, P=0.001 vs. B=-0.14, P=0.002) and ACR (B=0.56, P=0.004 vs. B=0.01, P=0.017) independent of other cardiovascular risk factors. After additional adjustment for 24-h PP, the association of AASI with eGFR-EPI had borderline significance (P=0.053), whereas the significant associations of 24-h PP with serum creatinine and ACR persisted (P=0.009 and P=0.006) after adjusting for confounding factors and AASI. Multiple logistic regression analysis showed that each s.d. increase in 24-h PP (that is, 13 mm Hg) was associated with a higher risk of suffering from microalbuminuria (MA) by 39% (P=0.038) after additional adjustment for AASI. In conclusion, AASI is more closely associated with eGFR compared with 24-h PP in hypertensive inpatients. However, for MA 24-h PP is a better predictor.