What possible basis could there be for the association between the amount of melanin in the skin and increased blood pressure that has been found by a number of investigators? The Table summarizes the findings of some of the studies of this association that have been reported since 1970. 1 Three of these studies 1-3 showed a positive association between the degree of pigmentation and level of blood pressure, while two reports by Keil et al 4,5 showed that blood pressure was associated with education and social class but not the degree of skin pigmentation. The study by Klag et al 6 in this issue ofThe Journalhas added to the literature on this topic by studying the blood pressure—skin pigmentation association in a much more controlled fashion. This relationship has been controlled for environmental factors previously demonstrated to contribute to elevated blood pressure. These variables include obesity, blood