Our purpose was to evaluate exercise-induced organ glucose metabolism using 18F-2-fluoro-2-deoxyglucose ([18F]FDG and three-dimensional positron emission tomography technique (3D-PET), comparing two analytical procedures. Eleven healthy male subjects were studied as controls (n=6) and exercise group (n=5). Exercise group subjects performed ergometer bicycle exercise for 40 minutes at 40% and 70% VSO2max. [18F]FDG (39.2 2.6 MBq) was injected 10 min after exercise. A whole body 3D-PET scan was performed immediately after exercise using PET scanner (SET-2400W, Shimadzu Co. Kyoto, Japan). PET image data was reconstructed by filtered 3D back projection algorithm with supercomputer (SX-4/128H4, Synergy Center, Tohoku Univ). Controls were studied using identical study criteria with exercise group. Two analytical procedures, semiquantitative (standardized uptake value; SUV) and quantitative (regional metabolic rate of glucose; rMRGlc) [Autoradiographic method (Phelps et al.)] were applied to assess organ glucose metabolism. ROIs (regions of interest) were drawn on lower limb muscles (e.g., thigh and lumbar/gluteal muscles) and viscera (e.g., liver, heart and brain). To compare analytical procedures, correlation coefficient analysis was done between SUV and rMRGlc data of lower limb muscles, brain and heart. Quantitative analysis revealed that rMRGlc was increased (p<0.05) in skeletal muscles of thigh and lumbar/gluteal region, and decreased in brain (p<0.05) at mild or moderate exercise loads. Semiquantitative analysis revealed the identical results except in lumbar/gluteal muscles. It was found a correlation between SUV and rMRGlc at thigh, brain and heart, however; correlation was not suggestive at lumbar/gluteal muscles. We validated the semiquantitative procedure (SUV) taking absolute quantification method of glucose metabolic rate as a standard. It was observed, the rMRGlc was increased in thigh muscles and decreased in brain at mild or moderate workloads. However, discrepancies between SUV and rMRGlc in one organ demonstrate, semiquantitative approach needs a great care when metabolic rate of glucose utilization changes at wholebody level.