[en] Objective: To investigate the influence of STAT3 antisense oligodeoxynucleotides (ASO- STAT3) on radiosensitivity of B16 cells. Methods: Oligodeoxynucleotides were tansfected into B16 cells with oligofectamine reagent. Cell survival was measured using CCK-8 assay. Apoptotic assays were performed using Hoechst33258 staining and Annexin V/PI with FACS analysis. Results: Cell survival decreased significantly in those groups tansfected with ASO-STAT3 and irradiated with different dose of T-rays. Compared with those cells treated with irradiation alone or AO-STAT3 transfection with subsequent exposure to radiation, fraction of early apoptosis increased in those cells treated with ASO-STAT3 transfection combined with irradiation. Conclusion These results showed that targeting ASO-STAT3 can enhance the therapeutic effect of 7-ray irradiation on B16 cells, which implied that STAT3 can act as a potential molecular target for tumor therapies, and also a potential molecular target for enhancement of radiosensitivity of radioresistant tumors. (authors)