An analysis was conducted using serum stored at 70 degrees Celsius, collected in 1985-86 (n=5115) and 1992-93 (n=4086). These analytes were stable in serum samples collected, handled and stored under conditions used in this study. Integrity of the chemical analysis throughout the study was maintained by proven laboratory quality control procedures. Monitoring analyte concentrations in serum from collections seven years apart allowed analysis of age and time dependent changes in serum antioxidants. These data were linked with extensive pre-existing sociodemographic, dietary, other behavioral and physiologic data for the cohort. Statistical analyses provided information on the population's serum antioxidant distribution, tracking, change and major determinants in diverse young adults. In addition, these data established baseline and 7-year change concentration values for followup of this large CARDIA cohort, though the relationship of these serum antioxidants to disease endpoints was not itself part of the work scope. Study of plasma ascorbic acid, which is not stable under our storage conditions, was initiated using fresh samples to be collected in 1995-96 (n=4000).