Previous studies showed that in patients with coronary artery disease(CAD), the ejection fraction(EF) response to exercise was often abnormal. Therefore, the fact that EF at rest might be infulence by extent of CAD was implied. So, we studied the relationship between the extent of CAD and the left ventricular function with LVEDP and LVEF measured by area-laength method in 168 patients with significant CAD without myocardial infarction and 111 cases with myocardial infarction. The results are as follows: 1) In 168 cases with significant CAD without myocardial infarction, LVEF in 87 cases with single vessel involvement is significantly higher than in 81 cases with multi-vessel involvement(76.4+/-10.0, 71.3+/-14.9), but LVEF in both group are within normal limits of ours(75.1+/-18.8). LVEDP has no difference between groups. 2) In 111 cases with myocardial infarction, there are no significant difference in LVEDP and LVEF between single vessel group and multi vessel group. But LVEF in both group are significantly lower than normal range of ours. In conclusion, LVEF in the group without myocardial infartion was infulenced by the extent of CAD. But LVEF in the group with myocardial infarction may be influenced by not only the extent of CAD but also infarction site, duration after infarction and collerteral vessels.