The study was renewed in 1992 to 1) extend morbidity and mortality surveillance by three years (to June 1994 for events through December 1992); 2) to extend analysis and publication of Five City Project (FCP) results and methods; and 3) to provide a small amount of incremental support to enable use of frozen plasma samples from earlier FCP population surveys to conduct a nested case-control study of the association of HDL subfractions and apolipoproteins with fatal and non-fatal cardiovascular disease. Extension of surveillance data collection was needed to insure the detection of any impact on morbidity and mortality of the significant risk factor changes that occurred in the treatment cities, compared to control cities, by 1986. The nested case-control study involved matching the survey and surveillance data sets to identify persons with documented events who participated in one of the five population surveys, identifying and contacting potential controls to be certain that they were free of CVD, and analysis of plasma samples frozen at -80 degrees centigrade for apolipoproteins A-I and B and HDL2,3 subfractions. This allowed multifactor assessment of the association between those factors and CVD in persons for whom many other variables were known.