Background: Visceral adipose tissue (VAT) is thought to confer increased insulin resistance and cardiovascular risk through leukocyte infiltration and increased adipose macrophage activity. Previous positron emission tomography (PET) studies using fluorodeoxyglucose (FDG) demonstrated that increased FDG uptake could reflect the severity of inflammation in the body. We hypothesized that exercise training could reduce VAT inflammatory activity as well as the body adiposity and it could be detected using combined FDG PET/computed tomography (CT). Methods: We observed 23 overweight women who participated in civil exercise training program. Anthropometric and lab data and FDG PET/CT were evaluated before and 3 months after an exercise program, consisting of aerobic exercise (45 min/session, 300 Kcal/day) and muscle strength training (20 min/session, 100 Kcal/day) 5 times per week. An one-hour torso PET/CT was performed after injection of FDG (370-555 MBq). The FDG uptake of VAT was measured using volumetric analysis tool of the PET/CT fusion image on a dedicated workstation and the maximum standardized uptake value (max SUV) in the regions of interest (ROI) was calculated. Results: At baseline, VAT SUV was significantly correlated to body weight (r=0.764, p<0.001), waist circumference (r=0.586, p=0.003) and body mass index (r=0.821, p<0.001). Follow-up VAT SUV levels significantly decreased from 1.11 to 0.46 (p<0.001) along with a reduction in weight, waist circumference, and BMI. Conclusions: These findings suggest that exercise training could reduce not only the body adiposity but also VAT inflammation. FDG PET/CT would be useful to evaluate the inflammatory status of VAT and the effects of therapeutic intervention targeting for that.