Abstract: Objective : To quantitative detect plasma EBV/DNA level and its application in early diagnosis, clinical staging, prediction prognostication and monitoring recurrence and metastasis in nasopharyngeal carcinoma. Methods : Using Fluorescent quantitative PCR , the content of plasma EBV/DNA were detected in 120 patients with primary NPC, 90 patients with follow up including 60 in clinical remission and 30 with distant metastasis and local recurrence. Results :Plasma EBV/DNA was detectable in 96% (115/120) of primary NPC, 95% (21/22) of NPC with distant metastasis, and 100% (8/8) of recurrent NPC, the detectable proportion in these groups was significantly higher than that in control subjects. In primary NPC patients, patients in advanced TNM stage had significant higher plasma EBV/DNA concentration than those of in early TNM stage;The plasma E B V/D N A concentration of patients had local recurrence and/or distant metastasis after treatment were significant higher than those with no evidence of local recurrence and/or distant metastasis, 2 year disease free survival rate were significant lower in patients with plasma EBV/DNA concentration more than 40 000copies/ml compared with those with less than 40 000copies/ml ( 45.1 % vs 92.9% ). For those follow-up patients after treatment, the detectable proportion and concentration in recurrent and metastatic NPC patients were significantly higher than that of in clinical remissive NPC patients. Conclusions : Our results suggest that the quantum of plasma EBY- DNA is a sensitive, valuable and reliable tum or marker for reinforcing clinical diagnosing, staging, prediction prognostication of early treatment failure as w ell as monitoring of metastasis and recurrence in endemic area NPC patients.