One hundred twenty-four patients with lung cancer undergoing operation in our hospital were prospectively studied on evaluation of the ischemic heart disease before operation. They performed master double electrocardiogram and exercised T1 scintigram before operation. The patient with positive master double electrocardiogram and/or exercised T1 scintigram was taken into high risk group. All patients in high risk group performed coronary angiography. This high risk group consisted of 37 patients (29.8%), including 6 single vessel disease (4.8%), 2 double vessel disease (1.6%), and 1 triple vessel disease (0.8%). Preoperative revascularization was done 8 patients (6.5%). These revascularization patients had uneventful course during and after lung operation. However 2 cases of vasospastic angina (VSA) occurred in non-risk group during operation. It was impossible to anticipate VSA before lung operation in our series. Therefore our preoperative evaluation and care of organic ischemic heart disease was effective in preventing cardiac complications.