We studied hypertrophic patterns in the electrocardiograms of 60 Nigerian hypertensives. Thirty were in heart failure and 30 without failure (matched for age and sex). Combined left ventricular and left atrial hypertrophy was the commonest finding occurring in 58.3%, followed by left ventricular hypertrophy alone in 30%. 76.7% and 40% had combined left ventricular and left atrial hypertrophy in the heart failure and the non-heart failure groups, respectively (P less than 0.02). Though these changes increased with increased blood pressure, the latter is similarly severe in both groups. 100% of patients in Class IV failure had combined left ventricular and left atrial hypertrophy. The 3 patients who had additional right atrial hypertrophy were in Class IV failure, 2 of whom died during follow-up. These changes are much more marked at presentation than reprots in caucasians and even in previous reports in Africans. The changes reflect the long-standing nature and severity of the hypertensive process, and point to the fact that the majority of hypertensives in this environment present rather late.