The prospective observational follow-up of the Trials of Hypertension Prevention (TOHP) includes cardiovascular events among the 4, 507 surviving participants from the ten clinical centers involved in Phases I and II of TOHP. Phase I was a randomized trial of the effects of non- pharmacologic interventions, including sodium reduction and weight loss, on BP over 18 months of follow-up with 2,182 participants. Phase II examined the effects of sodium reduction and weight loss on BP over a longer 36-month period in a randomized 2X2 factorial design with 2,382 participants. During follow-up in Phases I and II of TOHP, several measures of both weight and sodium excretion were carefully obtained on all participants. The prospective observational follow-up specifically examines whether these values, with an emphasis on average level of sodium excretion and weight changes are predictive of later cardiovascular disease. The follow-up is conducted centrally by mail from the Division of Preventive Medicine, which served as the Coordinating Center for Phases I and II, and which has been very successful in conducting such large-scale studies by mail. Information on cardiovascular events subsequent to the trial periods is collected through June, 2003, representing an average follow-up of approximately fourteen years from the end of Phase I and eight years from the end of Phase II. This cohort provides a unique resource to address the impact in a normotensive population of salt restriction and weight change on subsequent cardiovascular events.