Several studies have shown associations of high levels of hemoglobin (Hgb) or blood viscosity with cardiac events and with left ventricular (LV) hypertrophy (LVH). To assess the relations of LV mass and function with Hgb delivery (ie, the physiological carrier of oxygen), we calculated the product of Hgb concentration and Doppler-derived cardiac output in 864 hypertensive participants with electrocardiographic LVH (359 women) in the Losartan Intervention for End Point Reduction in Hypertension echocardiography substudy. Among women, Hgb delivery was positively related to internal dimension, septal and posterior wall thicknesses, LV mass, endocardial and midwall fractional shortening, and peak A wave velocity and negatively to total peripheral resistance index, E/A ratio, deceleration time, and the isovolumic relaxation time. Among men, Hgb delivery was positively related to LV internal dimension, LV mass, and A velocity, and negatively to LV midwall shortening, relative wall thickness, peripheral resistance index, and E/A ratio. In multivariable analyses that adjusted for age, diastolic blood pressure, body mass index, and total cholesterol, hemoglobin delivery in women was related positively to LV fractional shortening, midwall shortening, LV mass mitral valve A velocity, and LV internal dimension and negatively to mitral valve deceleration time and isovolumic relaxation time. Among men, Hgb delivery had positive independent relations to mitral valve A velocity, LV internal dimension, midwall shortening, and LV mass and negative relations to the E/A ratio and relative wall thickness. Thus, in hypertensive LVH, higher oxygen delivery capacity is associated with higher LV mass and impaired early diastolic LV filling.