Serum lipoprotein subfraction concentrations were measured in 1,961 men and 423 women who were employed or who applied for employment at Lawrence Livermore National Laboratory between 1954 and 1957. Computer files were created by Dr. Gofman at Donner Laboratory for epidemiologic studies of lipoprotein fractions. The files included name, age, gender and the following medical information: cholesterol, lipoprotein subfraction concentrations, blood pressure, weight, smoking history, hemoglobin, red and white blood cell counts, and blood proteins. Dr. Gofman provided those computer files for this study. The vital status and the history of coronary disease in the cohort were determined through state and national mortality surveillance systems, public records, medical and hospital records, autopsy reports, and telephone interviews with cohort members. All medical documents were examined by a physician and endpoints assigned according to international diagnostic criteria.