The National Institutes of Health Consensus Development Conference on Triglyceride, High Density Lipoprotein, and Coronary Heart Disease brought together experts in lipid metabolism, epidemiologists, and clinicians as well as other health care professionals and the public to address the following questions: (1) is the relationship of high triglyceride and/or low HDL cholesterol with coronary heart disease causal? (2) Will reduction of high triglyceride and/or elevation of HDL cholesterol help prevent coronary heart disease? (3) Under what circumstances should triglycerides and HDL cholesterol be measured? (4) Under what circumstances should active intervention to lower triglyceride and/or raise HDL cholesterol be considered in high risk individuals and the general population? (5) What can be accomplished by dietary, other hygienic, and drug treatments? (6) What are the significant questions for future research? Following two days of presentations by experts and discussion by the audience, a consensus panel weighed the evidence and prepared their consensus statement. Among their findings, the panel concluded that (1) existing data provide considerable support for a causal relationship between low HDL and CHD; however, with respect to TG data are mixed and the evidence on a causal relationship is incomplete; (2) initial TG and/or HDL levels modify benefit achieved by lowering low density lipoprotein cholesterol (LDL-C); however, evidence from clinical trials is insufficient to draw conclusions about specific benefits of TG and/or HDL altering therapy; (3) HDL-C measurement should be added to total cholesterol measurement when evaluating CHD risk in healthy individuals provided accuracy of measurement, appropriate counseling, and followup can be assured; (4) there is general agreement with the Adult Treatment Panel (ATP) guidelines that LDL-C is essential in cardiovascular risk assessment, as well as that persons with elevations of LDL-C greater than 150 mg/dl refractory to nondrug therapies may require drug treatment; (5) there is a strong consensus that hygienic approaches (diet, exercise, smoking cessation, weight loss) should be employed to lower TG and/or raise HDL; there is no consensus for the use of drug treatment in patients with borderline hypertriglyceridemia and low HDL-C levels in the presence of a desirable LDL-C level.