It is essential to predict the treatment efficacy of pancreatic carcinoma early.The purpose of this study was to examine whether 18F-FDG (2'-deoxy-2'-[18F]fluoro-D-glueose) or 18F-FLT (3'-deoxy-3'-18F-fluorothymidine) PET can be used for chemosensitivity testing by investigating the binding characteristic of 18F-FDG or 18F-FLT with Patu 8988 human pancreatic carcinoma cell and the influence of gerncitabine in the uptake of 18F-FDG or 18F-FLT on Patu 8988.Under the conditions of 1×106cells,3.7 kBq 18F-FDG or 18F-FLT,and incubation at 37℃ for 100 min,the cell uptake of 18F-FDG and 18F-FLT was (60.60±3.05)％ and (50.57±2.81)％,respectively.There was a significant decrease in TKI-LI (thymidine kinase 1 labeling index) 24 h after administration of gemcitabine.The uptakes of 18F-FDG and 18F-FLT were negatively correlated with the doses of gemcitabine (r=-0.928 for 18F-FDG,r=-0.876 for 18F-FLT,P＜0.01).When same doses of gemcitabine were administered,the 18F-FLT uptake inhibition rate was significantly higher than that of 18F-FDG (P＜0.01).These results indicate that the response to gemcitabine could be predicted as early as 24 h by 18F-FDG or 18F-FLT PET scans.18F-FLT is more sensitive than 18F-FDG to predict the response to therapy.