PURPOSE: The purpose of this study was to evaluate the incidcnce of extrapericardial fat in the left cardiacborder, and with regard to left extrapericardial fat, to correlate chest radiographs with CT scans. MATERIALS AND METHODS: This study involved 132 consecutive patients who underwent chest PA and lateral radiographs, and chestCT scans. According to the results of chest PA radiograph, patients were divided into three groups: those with aclear left cardiac border; those with an indistinct left cardiac border; and those with an indistinct left cardiacborder with increased density; cardiophrenic angle, as seen on lateral radiograph, the presence of increaseddensity in the anterior cardiophrenic angle, as seen on lateral radiograph radiographs was evaluated. On the basisof the results of CT scanning, patients were classified into four groups according to the amount of leftextrapericardial fat: negative, minimum, moderate, and maximum. Left extrapericardial fat, as seen on CT, wascorrelated with the conspicuity of left cardiac border seen on PA radiograph and the presence of increased densityin the anterior cardiophrenic angle, as seen on lateral radiograph. RESULTS: On CT, left extrapericardial fat wasobserved in 51 patients (38.6%). In 38 of these (28.8%), the amount was minimal, in 12 (9.1%), it was moderate,and in one (0.8%), it was maximal. On posteroanterior chest radiograph, clear, indistinct, and indistinct andincreased density of the left cardiac border was seen in 89 (67.4%), 28 (21.2%), and 15 cases (11.4%),respectively. On lateral radiograph, increased density of the anterior cardiophrenic angle was seen in 115 cases(87.1%) but in 17 (12.9%), increase density was not apparent. There was significant correlation between chestradiographs and CT(p<0.001) (sensitivity: 53%; specificity: 100%; positive predictive value: 100%; negativepredictive value: 84%). CONCLUSION: The conspicuousness of the left cardiac border, as seen on PA chestradiograph, correlated with the presence of left extrapericardial fat, as seen on CT, and was related to theamount of left extrapericardial fat. Increased density of the anterior cardiophrenic angle, as seen on lateralradiographs, correlated with the presence of left extrapericardial fat on CT, but the absence of increased densityon lateral radiograph corresponds to the absence or a minimal amount of left extrapericardial fat, as seen on CT.