Many studies have paid attention to the prevalence of left ventricular hypertrophy (LVH) as assessed by electrocardiogram (ECG) in hypertensive patients. Patients with ECG-LVH show a considerably higher risk of cardiovascular morbidity and mortality than patients without ECG-LVH. This paper describes the prevalence of LVH and the relation between LVH, age, sex and BP. ECG, BP, treatment, duration of hypertension, body mass index and total serum cholesterol were recorded. The dimension of LVH was computed in accordance with the Minnesota Code. One of five hypertensive patients (21%) had LVH with or without repolarisation abnormalities. LVH based on high QRS voltages only was found more often in men. LVH with repolarisation abnormalities was more frequent in elderly patients. LVH was found more often in the highest SBP categories (SBP > 160 mmHg) and in the highest DBP categories (DBP > 105 mmHg). A logistic regression analysis showed the influence on the occurrence of LVH of the following parameters: being male, age > 65 years, SBP > 160 mmHg and DBP > 105 mmHg.