SUMMARY In a house-to-house study of 994 urban Zulus the prevalence of hypertension according to WHO criteria was 25% (23% men, 27% women). In a rural Zulu study of 987 the prevalence age corrected to the urban distribution was 9 4% (8.7% men, 10% women). Thus there was a pronounced difference between the prevalence of hypertension in the urban and rural Zulu (p <0.0005). There was an earlier onset of hypertension in the urban compared with the rural

In a study of 4,993 rural Zulus the over-all prevalence of primary hypertension was 8.37% (females 8.78%, males 7.4%). The mean arterial pressure in relation to age and sex was not as high as in urban Zulus. A diastolic blood pressure of greater than or equal to 95 mm Hg was present in 4.99% of the subjects and 1.46% had a diastolic blood pressure of greater than or equal to 110 mm Hg. This study suggests that hypertension is not a major health problem in rural Zulus and that large case-finding and intervention programmes should be confined to the urban Black population of South Africa.