Secondary data analyses were performed on family data obtained in an ongoing hypertension genetic study conducted at the University of Utah with Roger R. Williams as principal investigator. The available data represented one of the largest studies of cardiovascular reactivity among genetically related individuals. During 1981-83, a total of 2,548 subjects, members of 98 extended families (multiple generations and multiple nuclear families) participated in an extensive cardiovascular examination and were assessed on a comprehensive battery of cardiovascular tests. Annual follow-up questionnaires obtained information about the onset of hypertension and new medication prescribed. In 1991-92, a follow-up exam was conducted on 1,500 subjects.