We examined the contribution of arterial wave reflection to early abnormalities in left ventricular relaxation, whether this association was modified by gender or hypertension and the role of reflected wave timing and amplitude. We studied a cohort of normotensive and untreated essential hypertensive Taiwanese participants (675 men, 601 women, mean age 52 years). Doppler flow and applanation tonometry were performed to assess carotid-femoral pulse wave velocity (PWV) and augmentation index (AI). Diastolic parameters including the ratio between the peak velocity of early and late diastolic mitral inflow (E/A), E-deceleration time and left atrial (LA) diameter were measured by echocardiography. In multivariate models predicting E/A, women were more likely to have lower E/A than men (β=-0.08, P<0.001). AI was significantly associated with lower E/A in both men (β=-0.09, P=0.005) and women (β=-0.12, P<0.001) independent of PWV. Inclusion of AI in the overall model reduced the gender difference in E/A by 61% and rendered it nonsignificant. There was a significant interaction between AI and hypertension (P=0.02). The inverse association between AI and E/A was significant only in normotensive men and women, and only for the amplitude but not timing of the reflected wave. In conclusion, the contribution of wave reflection to left ventricular diastolic dysfunction was independent of arterial stiffness, more pronounced in normotensive individuals and explained a significant portion of the gender difference in diastolic function.