Are there ethnic differences in the pathogenesis of hypertension and are these sufficient to influence choice of treatment? I will also consider prevalence and complications. Because hypertension is the biggest and an almost entirely treatable cause of cardiovascular disease, even small ethnic differences in its optimum management have large implications for health resources. Ethnic differences in the type of hypertension give us the strongest evidence that we have for the concept that hypertension exists in two broad types. As for diabetes, hypertension can usefully be considered as of type 1 or type 2, each with its own preferred treatment. Results of recent trials support this view and emphasise the importance of choosing the right strategy for the type of hypertension to be treated. Numerous published studies, including many reviews, compare one or more of the four parameters to be discussed in different ethnic groups. A few have prospectively identified similar numbers in the ethnic groups being compared or a minimum proportion of the ethnic minority. But most are retrospective analyses of studies in which a multi-ethnic population was recruited. I found relevant studies with Medline and Google-Scholar, searching for “hypertension” with either “ethnic” or the names of individual ethnic groups. White and black people are the key ethnic groups to have been compared. Some prevalence studies included Asians, but these studies give insufficient information on which to make reliable statements about pathogenesis or treatment. Progress in understanding the pathogenesis of hypertension has been slow because essential hypertension is extremely complex at a molecular level.1 Conversely, hypertension exists in only two broad physiological types. This has been long predictable in theory from Poiseuille's law (that blood pressure is the product of vasoconstriction and volume) and supported in practice from the observation that a few of the syndromes where hypertension is …