Abstract: Objective: To observe the inhibitory effect of radiotherapy on renal carcinoma and expression of TNF-α in BALB/c mice. Methods: Renal carcinoma-barring mice were treated with local fractionated tumor irradiation.The mice were euthanized on day 28. Cultured Renca cells were exposed to a single radiation dose of 20Gy after cultured for 24h.Expression of TNF-α protein in tumors and Renca cells was detected by Western blot. Results: Radiotherapy inhibited the growth of renal carcinoma in BALB/c mice.Local radiotherapy significantly increased the expression of TNF-α in tumor tissue.The expression of Renca cells cultured in vitro was significantly up-regulated after radiotherapy. Conclusion: X-rays can stimulate tumor tissue to secrete TNF-α and are correlated with the up-regulation of TNF-α expression in tumor tissue.