Abstract: In recent years, ¹⁸F-fluoro-3'-deoxy-3'-L-fluorothymidine (¹⁸F-FLT) has been developed as a proliferation tracer, hnaging and measurement of proliferation with PET could provide us with a non-invasive tool to value tumor cell proliferation rate and to monitor the response to anticancer treatment. In this review, the basis of ¹⁸F-FLT as a proliferation tracer is discussed. Furthermore, an overview of the current status of ¹⁸F-FLT PET research is given. The results of research show that ¹⁸F-FLT PET can correctly reflect cellular proliferation, it also has certain limitations. In comparisonwith ¹⁸F-FDG, ¹⁸F-FLT uptake is lower in most cases. Furthermore, ¹⁸F-FLT uptake does not reflect all kinds of cell proliferation.