In 1986, the total surviving cohort of NHANES I (approximately 12,500) were re-contacted in order to improve risk factor morbidity and mortality analyses. The NHLBI contributed to funding the NHANES III and currently contributes to funding NHANES IV. NHANES III incorporated features which distinguished it from earlier surveys in the series. The features included a longitudinal component, meaning that individuals were followed over time for vital statistics and re-examination, long-term biological specimen banking, and oversampling of Blacks and Hispanics. The component of additional questions and procedures provided information on the common heart, vascular, lung, and blood diseases, risk factors and elements of medical care. It also indicated how representative the NHLBI population-based epidemiologic studies were and to what extent the findings of these studies could be generalized to the United States population. The major NHLBI ongoing studies which were compared with NHANES III were the Coronary Heart Disease Risk Factor Development in Young Adults (CARDIA), Atherosclerosis Risk in Communities (ARIC), the Framingham Heart Study, and the Cardiovascular Health Study.