Objective: Body adiposity, especially ectopic fat accumulation, has a range of metabolic and cardiovascular effects. This study aimed to investigate whether thyroid function is associated with various regional fat quantities in euthyroid subjects. Methods: A total of 100 euthyroid men (free triiodothyronine (fT3), 4.77±1.21 pg/ml; free thyroxine (fT4), 1.38±0.21 ng/dl; and TSH, 2.09±0.91 μIU/ml) were enrolled in this cross-sectional study.We measured accumulated regional fat using 64-slice multi-detector computed tomography. Multiple linear regression analysis was used to determine whether accumulated fat in each region was associated with clinical parameters after adjusting for age. Results: FT3 was inversely correlated with BMI (r=-0.232, P=0.029) and LDL cholesterol level (r=-0.277, P=0.019). FT4 was inversely correlated with waist circumference (r=-0.350, P=0.008) and BMI (r=-0.355, P<0.001). In multiple linear regression analysis, fT3 and fT4 levels were significantly associated with pericardial fat volume (fT3: B=-0.079, 95% CI -0.142 to -0.017, P=0.013; fT4: B=-0.411, 95% CI -0.780 to -0.042, P=0.030) in euthyroid men, independent of age. FT3 level was inversely associated with intramuscular fat area (B=-0.059, 95% CI -0.106 to -0.011, P=0.016) and hepatic fat quantity (B=-0.237, 95% CI -0.441 to -0.033, P=0.024) in euthyroid men, independent of age. Conclusions: In euthyroid men, low levels of fT3 and fT4 were significantly associated with increased pericardial fat volume and BMI.