Intestinal chylomicrons and their remnants are believed to contribute both directly and indirectly to the onset and development of atherosclerosis. Measurement of postprandial triglyceridemia or the plasma concentration of apoB-48 (the principle structural protein of chylomicrons) is not however standard clinical practice. The reason is that a standardized fat tolerance test has not been established, and age- and gender-specific normal ranges have not been determined. Appropriate cost-benefit analysis is also lacking, although such analysis depends upon reliable prospective data demonstrating that plasma parameters measured after a defined oral fat load can predict the presence of cardiovascular disease (CVD) better than existing lipid and non-lipid risk factors. In addition to being of prognostic value, positive prospective data linking plasma chylomicron levels and CVD would be of therapeutic importance and would reemphasize advice to restrict the size, frequency and fat content of individual meals.