Objective To investigate the effect of ionizing radiation on the expression of transcription factor STAT3 target genes in the pulmonary adenocarcinoma cell line A549.Methods The expressions of VEGF,Bcl-2 and Survivin in A549 cells with or without STAT3 inhibition were detected by RT-PCR and/or Western blot 24 h after 2 or 4 Gy of γ-ray irradiation.Results After γ-ray irradiation with 2 or 4 Gy,the expression of VEGF and Survivin increased significantly.However,the expression of Bcl-2 was not affected by γ-ray irradiation.Furthermore,the increased expression of VEGF and Survivin induced by radiation was found to be inhibited after radiation-induced activation of STAT3 was blocked by AG490 inhibiter.Conclusions γ-ray irradiation could up-regulate the expression of Survivin and VEGF via activating STAT3.The increase of Survivin might partly inhibit the radiation-induced apoptosis of A549 cells,and the up-regulation of VEGF might contribute to the tumor angiogenesis.