Most of us are well aware of the many studies showing that segregated groups of people who live with meager intakes of salt usually maintain entirely normal blood pressures throughout their lives (1-4). At the other extreme, populations in which salt intake is greater than the norm have an especially high incidence of hypertension (5, 6). One of the most graphic examples of relationships between salt intake and blood pressure was recorded by Prior and his colleagues (1, 2): the natives living on the island of Pukapuka and some other Pacific islands have a daily salt intake many times less than that of persons living in the Western culture, and their arterial pressures do not increase as they age. Yet, many of these natives have migrated to New Zealand and have taken up the cultural and dietary habits of the European New Zealanders. Subsequently, these migrants expe rience an incidence of increasing arterial pressure similar to that in the other new Zealanders of different racial stock.