Lipoprotein(a) (Lp(a)) is recognized as a new coronary risk factor, but few studies have quantitatively assessed the relationship of serum Lp(a) levels with other coronary risk factors in many patients undergoing coronary cineangiography. Seventeen coronary risk factors were quantified (i.e., age, gender, hypertension, impaired glucose tolerance, cerebrovascular accident, hyperuricemia, smoking, family history of ischemic heart disease (IHD), history of hyperlipidemia, Lp(a), total cholesterol, high density lipoprotein (HDL)-cholesterol, triglyceride, low density lipoprotein-cholesterol, apolipoproteins(apo)A-I,B, E) to determine their relationship with the numbers of involved coronary vessels using multiple regression test in 1,006 patients who underwent coronary cineangiogram (280 non-IHD patients: 144 men, 136 women; 726 IHD patients: 460 men, 266 women; age 16-84 years, mean 60.5+/-0.3). Multiple regression test indicated R = 0.506 and items that showed high beta weight and significant p level were age, Lp(a), impaired glucose tolerance, total cholesterol, cerebrovascular accidents, HDL-cholesterol, smoking, gender, family history of IHD, and apo-A-I (0.221, p<0.001; 0.174, p<0.001; 0.616, p<0.001; 0.138, p<0.001; 0.122, p<0.001; -0.12, p<0.001; 0.092, p<0.01; 0.091, p<0.01; 0.067, p<0.05; -0.065, p<0.05; respectively). It was concluded that Lp(a) is an independent, potential, and modifiable coronary risk factor, and that reduction of serum Lp(a) is important in the clinical management of patients with IHD.