Objective To evaluate the ability to kill human urothelial carcinoma T24 cells selectively in vitro by celecoxib combined with ZD55-IL-24 and explore the effectiveness for this combination use.Methods The EGFP expression of cells was observed by fluorescence microscope.The human umbilical vein endothelial cells (HUVEC) were used as crotrols.The expression of IL-24 mRNA was detected by RT-PCRwhen the cells were transfected by ZD55-EGFP or ZD55-IL-24.After transfected by ZD55-IL-24 and treated by celecoxib,the inhibition effect on cells was measured by MTT assay,and the apoptosis rate was examined by flow cytometry.Results The fluorescence in T24 and HUVEC can be observed 24h after ZD55-EGFP transfection and the fluorescence intensity was increased corresponding with the times.Fluorescence intensity in T24 cells showed higher than that in HUVEC group at the same times.The result of RT-PCR showed that the T24 cells expressed higher level of IL-24 mRNA than HUVEC group at the same time when the cells were transfect by ZD55-IL-24 (P ＜ 0.01).The inhibition rate of ZD55-IL-24 combined with celecoxib group was significantly higher than other groups (P ＜ 0.001).The inhibition rate of T24 cells in each group was significantly higher than HUVEC group (P ＜ 0.01).The flow cytometry results indicated that celecoxib combined with ZD55-IL-24 had the highest apoptosis rate on T24 cells than other single use group.Apoptosis rate of T24 cells showed a higher than HUVEC cells (P ＜ 0.01).Conclusion Celecoxib combined with ZD55-IL-24 can inhibit T24 cells proliferation at a greatest degree and this effect may be contributed to apoptosis.