The Framingham Study established hypertension as a major cardiovascular risk factor and quantified its atherogenic cardiovascular disease potential. An historical perspective is presented on the epidemiological insights about hypertension derived from 50 years of Framingham Study research into the prevalence, incidence, determinants and hazards of hypertension. Existing misconceptions about the presence of critical levels of blood pressure, the impact of the systolic and diastolic components of blood pressure, the hazard 'mild' hypertension, the impact in advanced age and the hazard of left ventricular hypertrophy. The importance of isolated systolic hypertension and the pulse pressure were demonstrated. It has been demonstrated that hypertension seldom occurs in isolation of other atherogenic risk factors, with which it tends to cluster. This clustering with other metabolically linked risk factors has been shown to reflect insulin resistance promoted by weight gain and abdominal obesity. Obesity was shown to be one of the major determinants of hypertension in the general population. Left ventricular hypertrophy was shown to be an ominous harbinger of cardiovascular disease rather than an incidental compensatory phenomenon. Multivariate risk profiles for coronary disease, stroke, peripheral artery disease and heart failure have been devised to facilitate incorporation of elevated blood pressure in a global, multivariate cardiovascular risk assessment.