We determined the myocardial metabolic rate for glucose (MMRGlc) in the ischemic or infarcted myocardium using 18-F-fluorodeoxyglucose (18-FDG) with positron emission tomography (PET), and studied energy metabolism in the ischemic myocardium. In some cases, we compared glucose metabolism images by 18-FDG with myocardial blood flow images using 15-oxygen water. Two normal subjects, seven patients with myocardial infarction and four patients with angina pectoris were studied. Coronary angiography was performed within two weeks before or after the PET study to detect ischemic areas. PET studies were performed for patients who did not eat for 5 to 6 hours after breakfast. Cannulation was performed in the pedal artery to measure free fatty acid, blood sugar, and insulin. After recording the transmission scan for subsequent correction of photon attenuation, blood pool images were recorded for two min. after the inhalation of carbon monoxide (oxygen-15) which labeled the red blood cells in vivo. After 20 min., oxygen-15 water (15 to 20 mCi) was injected for dynamic scans, and flow images were obtained. Thirty min. after this procedure, 18-FDG (5 to 6 mCi) was injected, and 60 min later, a static scan was performed and glucose metabolism images were obtained. Arterial blood sampling for the time activity curve of the tracer was performed at the same time. According to the method of Phelps et al, MMRGlc was calculated in each of the region of interest (ROI) which was located in the left ventricular wall. MMRGlc obtained from each ROI was 0 to 17 mg/100 ml/min. In normal subjects MMRGlc was 0.4 to 7.3 mg/100 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)