The relationship of coronary artery disease to plasma lipoproteins was examined in 43 men admitted to our unit with suspected ischemic heart disease. Coronary arteriography was performed, and a score reflecting the severity of disease was assigned to the angiogram. Plasma, obtained after a 12-h overnight fast, was assayed for triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, and HDL-3 cholesterol. HDL-2 cholesterol was found by subtraction. The cholesterol contents of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) were quantitated by the Freidwald equation. Men with high coronary scores tended to be older, and subjects with moderate coronary disease had significantly higher total and LDL cholesterol values than those with minimal disease. Age was the only factor to be significantly associated with coronary score and there was no significant association between coronary score and total LDL and HDL cholesterol or its subfractions when the age factor was taken into account.