Abstract: Objective: To investigate the correlation between the level of serum interleukin-10 (IL-10) and clinical biological behavior in nasopharyngeal carcinoma (NPC). Methods: The level of serum IL-10 was detected by ELISA in 60 patients with NPC and 20 cases in the control group. Results: The level of serum IL-10 in NPC was significantly higher than that in the control group (P<0.005). The level of serum IL-10 for the patients in stageⅠand Ⅱwas significantly lower than that for the patients in stage Ⅲ and Ⅲ (P=0.011). The level of serum IL-10 in patients with lymph node metastases or distant metastases was higher than that in patients without lymph node metastases or distant metastases, but no statistically significance was observed. Conclution: Rising level of serum IL-10 may play an important role in the development of NPC, and further studies may be necessary to determine the value of the level of serum IL-10 in NPC.