AIM: The aim of the study was to compare standardized uptake values (SUVs) in liver tissue obtained using whole-body unenhanced low-dose computed tomography (CT) with those obtained using contrast-enhanced high-dose CT for PET attenuation correction in PET/CT scanning. MATERIALS AND METHODS: Ten patients scheduled for F-FDG PET and contrast-enhanced CT of the abdomen were included in this study. PET data were corrected for attenuation using both unenhanced low-dose CT images and contrast-enhanced high-dose CT images. Differences in SUVmean and SUVmax were compared in three liver regions. RESULTS: The average SUVmean and SUVmax of all regions were 2.43 and 2.91 g/cm in the unenhanced data set and 2.53 and 3.17 g/cm in the enhanced data set, respectively. CONCLUSION: SUVmean and SUVmax were significantly elevated in liver tissue when using PET images corrected for attenuation with contrast-enhanced high-dose CT compared with PET images corrected with unenhanced low-dose CT. Although the differences may not be relevant in daily clinical practice, unenhanced and contrast-enhanced CT should not be selected randomly for attenuation correction if exact quantitative results are required.