Left ventricular hypertrophy (LVH) measured by electrocardiography (ECG LVH) in hypertensive patients has been shown to be associated with an increased risk of cardiovascular sequelae. Analysis of the determinants predisposing to ECG LVH may be helpful in the prevention of LVH. The Department of Health and Social Security Hypertension Care Computer Project studied 2994 hypertensive patients in whom an electrocardiogram was recorded while not on treatment. LVH was determined as the voltage sum SV1+ RV5 or RV6≥ 35 mm using Sokolow–Lyon voltage criteria. The relations were determined between the presence of LVH or voltage sum and different variables. Untreated systolic (SBP) and diastolic (DBP) blood pressure and pulse pressure were positively related to the increasing ECG voltage, while body mass index (BMI) and serum cholesterol were inversely related. Blood glucose and age did not correlate significantly. Patients with the presence of ECG LVH were more often men, black people, smokers and users of alcohol. In multiple logistic regression analyses, SBP, DBP, male gender and black race were positively, whereas BMI was negatively related to the presence of LVH. The positive relation of smoking and negative relation of serum cholesterol concentration to the presence of ECG LVH were apparent in men but not in women. This study confirms the adverse association between ECG LVH and SBP and DBP, male gender, black race and decreased BMI. It also addresses the less well-known associations of blood glucose, cholesterol, smoking and alcohol consumption.