Epstein Barr Virus (EBV) has oncogenic properties and the capacity to transform normal, resting B-cells into permanent lymphoblastoid cell lines. Six virus-encoded Epstein Barr nuclear antigens (EBNA) and three latent membrane proteins (LMP) are known. One important EBV-associated epithelial tumor is the nasopharyngeal carcinoma (NPC). EBV expresses only the proteins EBNA-1 and LMP-1 in NPC tumor cells. Tumors morphologically/histologically similar to NPC can also be found in the stomach, oesophagus, salivary glands, lung and in thymus glands.