Abstract: In order to investigate the feasibility of ¹⁸F-FLT MicroPET in the early efficacy of the antineoplastic drug. Twelve A549 lung carcinoma-loaded mice were randomly divided into 2 groups(control and treatment group, n=6 in each group). Cisplatin (DDP, 25 mg/kg) and saline were injected intragastricaly everyday to the treatment and control group, respectively. Tumor volume and weight were detected everyday and ¹⁸F-FLT MicroPET scans were performed at 0, 2, 5, 9, 14 d. The MicroPET results showed that after the second administration, the tumor uptake of treatment group decreased 21.28%, from （4.91±0.71）%ID/g to （3.87±0.61）%ID/g, while tumor volume was significantly decreased until 9 d (P<0.01). Compared with traditional method, MicroPET can detect much earlier and more accurate efficacy of antitumor agents.