Objective : To investigate the changes of α2-macroglobulin in different stages of radiotherapy in patients with nasopharyngeal carcinoma, and to explore its feasibility as a marker of serum markers reflecting radiotherapy injury. Methods : We collected the blood samples of 23 cases of newly diagnosed patients with nasopharyngeal carcinoma before the simple radiotherapy, the 10, 20, 30 and 33 times after simple radiotherapy, detected the α2- macroglobulin levels. The difference among the five stages was analysed by paired t-test using SPSS17.0 software package. Results : The serum level of α2- macroglobulin elevated with the increase of number of radiotherapy. After 10 times’ radiotherapy, the serum α2-MG concentration in patients with nasopharyngeal carcinoma was significantly higher than that before radiotherapy (12.04 ± 5.72 vs. 10.81 ± 5.38 U/L), the difference was statistically significant (t=4.818, P < 0.05). After 20 times’ radiotherapy, the serum α2-MG concentration in patients with nasopharyngeal carcinoma was significantly higher than that before radiotherapy (12.26 ± 5.77 vs. 10.81 ± 5.38 U/L), and the difference was statistically significant (t=5.237, P < 0.001). After 30 times’ radiotherapy, the serum α2-MG concentration in patients with nasopharyngeal carcinoma was significantly higher than that before radiotherapy (12.91 ± 5.55 vs. 10.81 ± 5.38 U/L), the difference was statistically significant (t=6.076, P < 0.05). At the end of radiotherapy, the serum α2-MG concentration in nasopharyngeal carcinoma patients was significantly (13.43 ± 6.05 vs. 10.81 ± 5.38 U/L) higher than that before radiotherapy (t=5.189, P < 0.05). Conclusion The serum level of α2- macroglobulin changes with the radiotherapy, so it can be a serum marker reflecting the damage of maxilla induced by ionizing radiation.