Body surface potential maps (BSPMs) and the pathology of 32 dogs with coronary artery ligations were analyzed to research the application of BSPMs to acute myocardial infarction (AMI). The group consisted of 18 dogs with left anterior descending coronary artery (LAD) ligations, 8 with right coronary artery (RCA) ligations and 6 with left circumflex coronary artery (LCX) ligations. The abnormal distribution of negative potential and minimal potential were observed in all of the dogs. In dogs with RCA ligations, the abnormal negative potential displayed on the right-superior, right-inferior or right portion of the anterior thorax. In those with LAD ligations, the abnormal potential appeared on the left-superior, left-inferior, middle-superior or middle portion of the anterior thorax. In those with LCX ligations, the abnormal potential showed on the left-superior or left-middle portion of the thorax. A good correlation was observed between the area of myocardial lesion and the extent of abnormal negative potential distribution (r = 0.82, p less than 0.001). A close correlation was also found between the area of myocardial lesion and the duration of abnormal negative potential (r = 0.61, p less than 0.05). This study suggests that BSPMs are useful in the assessment of AMI in terms of diagnosis, location and extent of myocardial infarct.