Hypertension is more prevalent and severe in urban black populations compared to whites, and is associated with a greater degree of target-organ damage for any given blood pressure level. In general, compared to whites, blacks respond well to diuretics and calcium channel blockers and less well to beta-blockers and ACE inhibitors. The exact mechanisms that contribute to differences in blood pressure between blacks and whites are still not fully understood, given the multi-factorial aetiology of essential hypertension. Various lines of evidence suggest black patients are more salt sensitive than whites, which is due to a tendency to retain sodium in the kidney. Inherent differences in ionic transport mechanisms, the renal epithelial sodium channel, the reninangiotensin-aldosterone system and vasoactive substances may be a partial explanation, but analysis is compounded by disparate socio-economic conditions between blacks and whites. At present, there is no complete explanation for these differences and further research is required.