Data on the distribution of triglyceride and total, LDL and HDL cholesterol are presented for age groups 40 yr and older. The populations represented came from Framingham, Albany, Honolulu, San Francisco, Evans County and Puerto Rico. They include white, Japanese and black persons and both sexes. Blood samples and lipid measurements were obtained after overnight fast by a common protocol as part of a cooperative study of lipoprotein phenotyping.