.A second exam of the cohort was completed during 1981-1982. Of the original cohort of 1028 subjects, 792 or 77 percent were reexamined and approximately 5.5% had died. The objective of the second examination was to assess the change in cardiovascular risk factors over the ten year interval, assess the disease experience of the cohort and gather additional data on new cardiovascular risk factors as well as pulmonary function measurements and covariates. Examination two differed from examination one in that there was greater opportunity to standardize data collection for methods, laboratories, equipment, and time of examination. Greater emphasis was placed on pulmonary function testing. One objective of examination two that was not achieved was the determination of a sufficient number of cardiovascular events to do analyses of concordance of disease and analyses of disease occurrence in relation to risk factors. Analysis of data on 167 monozygotic pairs of twins and 176 dizygotic pairs of twins showed results similar to those of the first examination for systolic and diastolic blood pressure but, unlike the first examination, also showed significant genetic variance for total cholesterol and LDL cholesterol. HDL cholesterol continued to show no genetic variance.