Objective The present study is to investigate IL-24 gene(Ad5F35-hIL-24) effect on the topoisommeraseⅡα(topoⅡα) and Caspase-3 expression in glioma cell line U251. Methods After transfected the U251 glioma cells with the Ad5F35-hIL-24, the methyl thiazolyl tetrazolium (MTT) was used to analyse the inhibition rate of Ad5F35-hIL-24 on the cells. Hoechst 33258 fluorescent staining and flow cytometric assay were used to detect apoptosis. The immunohistochemistry assay was used to detect topoⅡα expression, and Western blotting was applied to detect the protein expression of topoⅡα and Caspase-3. Transwell experiment was used to test the invasiveness of the cells. Results It was found that the Ad5F35-hIL-24 could inhibit U251 cell proliferation and induce apoptosis in a dose dependent manner compared with the control groups. It showed that Ad5F35-hIL-24 could inhibit topoⅡα expression reveled by immunohistochemistry and Westeren blotting, while it increased Caspase-3 protein expression. The Transwell experiment showed that the Ad5F35-hIL-24 could reduce the invasiveness of the U251 glioma cells.Conclusion The exogenous IL-24 gene can inhibit the cell proliferation and induce apoptosis of U251 glioma cells. The to