Although still the subject of debate, most investigators accept that plasma triglyceride levels are a risk factor for coronary heart disease. Data from epidemiological studies such as the Framingham Heart Study, the Paris Prospective Heart Study and the Stockholm Heart Study have shown that patients with elevated plasma triglyceride levels have a higher incidence of coronary heart disease. In one study, coronary heart disease mortality fell by 36% after continued lowering of plasma triglyceride levels. In patients whose triglyceride levels fell greater than 30%, mortality decreased by 60%. The effect of triglycerides as a risk factor appears to be obscured in studies that use multiple cardiac end-points. Several studies demonstrated a stronger association between plasma triglyceride levels and coronary heart disease in patients with total cholesterol levels less than 5.7 mmol/L, or high density lipoprotein (HDL)-cholesterol levels less than 1 mmol/L. Angiographic data have confirmed these findings and show clearly that elevated triglyceride levels are frequently observed in men with coronary heart disease. Other studies have demonstrated that remnants of triglyceride-rich lipoprotein particles are cytotoxic and atherogenic in vitro and in vivo. Also, patients with familial dys beta-lipoproteinaemia, a condition characterised by high levels of triglyceride-rich very low density lipoprotein (VLDL) particles, have a high risk of atherosclerosis. Thus, there seems to be evidence supporting the atherogenic properties of cholesterylester-rich particles, or remnants thereof.