The potent growth-transforming properties of Epstein-Barr virus (EBV) and its role in pathogenesis of a range of B cell and epithelial malignancies are well established. By contrast, the association of this B lymphotropic virus with malignancies of T and NK cell origin was entirely unexpected. Although a number of mature T and NK lymphoma subtypes have been associated with EBV, evidence for a robust viral/tumour relationship is principally limited to extranodal NK/T lymphoma (ENKTL). Despite progress in diagnosis and classification, alongside an evolving understanding of ENKTL pathobiology, EBV's contribution to lymphomagenesis remains largely unresolved. Challenges relate to the rarity of this entity, a lack of clinical and biological correlative data and scarcity of fresh tissue for molecular and functional studies. Nonetheless, recent studies on viral and cellular gene expression have permitted new avenues of investigation into ENKTL pathobiology aiming to extend our understanding of disease biology and ultimately improve clinical outcomes.