Recently elevated plasma homocysteine concentration is considered an independent risk factor for atherosclerosis and thrombosis with coronary artery disease. Folate and vitamin $B_{12}$ are cofactors and closely related with metabolism of homocysteine. The purpose of this study is to evaluate the correlation between homocysteine and folate and vitamin $B_{12}$ in patients with ischemic heart disease. Twenty-six patients, in whom coronary angiographic finding revealed more than $50\%$ of stenosis at least in one coronary vessel were enrolled as the patient group, and thirty subjects, in whom angiographic finding revealed in not significant stenosis, but complained of chest pain, were selected as the control group. Fasting venous blood was obtained and measured the concentration of plasma total homocysteine, folate and vitamin $B_{12}$ by high performance liquid chromatography and fluorescence detection method. We examined the correlation between homocysteine and folate and/or vitamin $B_{12}$ in the control group and the patient group, respectively. Compared with the control group, the patient group had relatively higher plasma total homocysteine concentration ($10.7pm4.2;vs;9.6pm3.5$ umol/L), but showed no significant difference. Folate and vitamin $B_{12}$ concentration are low in the patient group, but showed no significant difference between patient and control group. Plasma total homocysteine concentration showed negative correlation with folate and vitamin $B_{12}$ in both the control group and the patient group, and showed significantly negative correlation in patient group {r = -0.550 (p < 0.01) vs r = -0.609 (p < 0.01)}. We knew that the plasma total homocysteine concentration were relatively elevated in patient group compared with the control group. Because plasma total homocysteine concentrations are closely negative correlated with folate and vitamin $B_{12}$ in the patient group, folate and vitamin $B_{12}$ supplement can lower the mortality and morbidity of ischemic heart disease. (Korean J Community Nutrition 10(6) : $963∼970$, 2005)