Electrocardiographic (ECG) left bundle branch block (LBBB) is associated with left ventricular hypertrophy (LVH), but its relation to left ventricular (LV) geometry and function in hypertensive patients with ECG LVH is unknown. Echocardiograms were performed in 933 patients (548 women, mean age 6677 years) with essential hypertension and LVH by baseline ECG in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study. LBBB, defined by Minnesota code 7.1, was present in 47 patients and absent in 886 patients. Patients with and without LBBB were similar in age, gender, body mass index, blood pressure, prevalence of diabetes, and history of myocardial infarction. Despite similarly elevated mean LV mass (126725 vs 124726 g/m 2 ) and relative wall thickness (0.4170.07 vs 0.4170.07, P ¼ NS), patients with LBBB had lower LV fractional shortening (3076 vs 3476%), ejection fraction (56710 vs 6178%), midwall shortening (1472 vs 1672%), stress-corrected midwall shortening (90713 vs 97713%) (all Po0.001), and lower LV stroke index (3877 vs 4279 ml/m 2 ) (Po0.05). Patients with LBBB also had reduced LV inferior wall and lower mitral E/A ratio (0.7570.18 vs 0.8770.38) (all Po0.05). The above univariate results were confirmed by multivariate analyses adjusted for gender, age, blood pressures, height, weight, body mass index, heart rate, and LV mass index. Among hypertensive patients at high risk because of ECG LVH, the presence of LBBB identifies individuals with worse global and regional LV systolic function and impaired LV relaxation without more severe LVH by echocardiography.