Frequency domain correlative cardiogram (FCG) is a new developing technique in noninvasive measurement. It is not clear that FCG diagnoses cardiac ischemia. This study was made cn dogs with different degree of coronary artery stenosis, the relationship between the changes of cardiac ischemia and FCG is discussed in this paper.In open chest dogs, an external stenosis was produced by a micrometer constrictor cn the left circumflex coronary artery or the left anterior dis-cending coronary artery, which caused three different degrees of coronary artery stenosis: namely mild, moderate and severe stenosis. Coronary blood flow (CBF), aortic pressure, left ventricular pressure, systolic time intervals, admittance plethysmography, two-dimensional echocardiography and FCG were synchronously recorded.The result showed that FCG did not change when CBF was slightly decreased; FCG had a significant change when CBF was decreased to 40% of resting value; there was a remarkable change in FCG when CBF was decreased to 80% of resting value. The amplitude of change in FCG was in concordance with that of decreased CBF. A positive correlation between the changes of FCG and CBF was found.So we think that FCG is a valuable diagnostic method for myocardial ischemia when CBF is obviously decreased. It can reflect the degree and extensiveness of myocardial ischemia. This is was not clear that FCG diagnoses cardiac ischemia. This study was made cn dogs with different degree of coronary artery stenosis, the relationship between the changes of cardiac ischemia and FCG is discussed in this paper. open chest dogs, an external stenosis was produced by a micrometer constrictor cn the left circumflex coronary artery or the left anterior dis-cending coronary artery, which caused three different degrees of coronary artery stenosis: and severe stenosis. Coronary blood flow (CBF), aortic pressure, left ventricular pressure, systolic time intervals, admittance plethysmography, two-dimensional echocardiography and FCG were synchronously recorded. The result showed that FCG did not change when CBF was slightly decreased; FCG had a significant change when CBF was decreased to 40% of resting value; there was a remarkable change in FCG when CBF w as decreased to 80% of resting value. The amplitude of change in FCG was in concordance with that of decreased CBF. A positive correlation between the changes of FCG and CBF was found. Wo we think that FCG is a valuable diagnostic method for myocardial ischemia when CBF is obviously decreased. It can reflect the degree and extensiveness of myocardial ischemia.