Objective:To evaluate the relationship between serum neopterin levels and nasopharyngeal carcinoma and its clinical significance. Method:The serum neopterin levels were determined in 54 patients with nasopharyngeal carcinoma (NPC group) and 32 healthy adults (normal group) by ELISA. Result:The serum neopterin levels in NPC group were significantly higher than that of in normal group (P<0.001). The serum neopterin levels in UICC-TNM stages were undifferentiated (P>0.05). The serum neopterin levels in patients with no lymph node metastasis were lower than that of in lymph node metastasis (P<0.05). The serum neopterin levels decreased significantly after disappearance of tumor and its lymph node treated by radiotherapy (P<0.01). Conclusion:Cellular immunity mediated by macrophages might be involved in the pathologenesis of nasopharyngeal carcinoma and the measurement of the serum neopterin may be a useful objective index to evaluate cellular immunological functions and curative effects.