This study deals with the effect of radiation treatment (RT) on serum transferrin and tumor necrosis factor-a (TNF-a) in patients with malignant tumors. In 21 patients who received 36-60 Gy in 20 to 30 sessions of RT, serum transferrin and TNF-a were determined pre-RT, after 10 to 15 sessions (middle of RT) and after 20 to 30 sessions (end of RT). The values of serum transferrin pre-RT were significantly higher than those in the middle and at the end of RT (p<0.001). The values of TNF-a were increased by RT and were significantly higher at the end of RT as compared to the pre-RT values (p<0.05). The values of serum transferrin and TNF-a show a tendency to negative correlation, either as a whole or seperately pre-and under-RT. However, no correlation was statistically significant.