Abstract: In the seven years of following 511 casese screened for EBV-IgA/VcA in Sihui Country. Only10% of them were keeping at the original level, 51.5% of them had changed from positive to ngeative then to positive again, or from negative to positive then to negative. Positives in first two years changing to negative ones composed 77.94%. 55% negaitives had changed to positives response were seen in 3-4 years. In our study about 38.46% of positive response changed to negative. Any association is there betwed both highest risk area of NPC, in the world highert rate of changing to negatire in Sihui needs to be studied in fature.