Abstract: The present invention features methods for diagnosing, detecting, monitoring and determining the prognosis of Epstein Barr virus associated cancers in a patient by detecting or measuring EBV DNA present in the serum or plasma of the patient followed by EBV subtyping of polymorphisms. The sensitivity of the circulating EBV DNA serves as a good screening tool while the EBV subtyping of polymorphism confirms the prognosis or diagnosis of EBV associated malignancies. The present invention also features diagnostic kits comprising suitable reagents for the above tests.