Purpose: There is increasing evidence that plaque inflammation could be assessed by F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET). Pericardial fat (PF) thickness is reported to be associated with coronary atherosclerosis. To our knowledge, no other study has measured pericardial fat (PF) inflammation or investigates its association with coronary artery disease (CAD). We investigated whether PF F-18 FDG activity could be related to CAD using time of flight (TOF) PET/CT scanner. Methods: In all 73 patients (39 with CAD (male 27, 52짹 7.9 yrs), 34 normal coronary (male 18, 53.8짹9.3 yrs) who underwent coronary angiography (CAG) were randomly studied. The TOF PET/CT images (Philips GEMINI TF) was performed within 1 week after CAG. Result: The FDG uptake of PF was measured using volumetric analysis tool of the PET/CT fusion image on a dedicated workstation. The PF was measured by manual tracing of a region of interest (ROI) at the pericardium on axial CT slices and then the maximum standardized uptake value (max SUV) in the ROI was calculated. Age and gender-adjusted max SUV of FDG on TOF PET/CT was significantly higher in the PF of patients with CAD than those of patients without CAD [(mean 1.21짹 0.59 (0.62 to 1.8) vs 0.27짹 0.12 (0.15 to 0.39), P<0.05)]. Conclusions: Patients presenting with CAD have increased inflammation activity in PF. Our findings might be contributed to understanding a linkage between pericardial fat and coronary artery disease.