Abstract: ¹⁸F -3'-deoxy-3'-L-fluorothymidine(¹⁸F-FLT)has been developed as a proliferation tracer in recent years. Imaging and measurement of proliferation with PET could provide clinicians with a non-inva-sive tool to monitor the response to anticancer treatment. In this review, the basis of ¹⁸F-FLT as a proliferation tracer is discussed. And reviewed the current status of ¹⁸F-FLT preclinical researches. Although ¹⁸F-FLT is a tracer that visualizes cellular proliferation, it also has certain limitations, for example, in comparison with the most widely used PET tracer ¹⁸F-FDG, ¹⁸F-FLT uptake is significant lower in some tumors, and ¹⁸F-FLT up-take does not always reflect the tumor cell proliferation rate cause of the different chemothe-rapy regimens.