Subsequent to its discovery over 45 years ago, Epstein-Barr virus (EBV) has been associated with numerous human carcinomas. Approximately 95% of the world's population sustain an asymptomatic life-long EBV infection. EBV persists in the memory B cell pool of normal healthy individuals and any disruption of this interaction results in virus-associated B cell tumours. The association of EBV with epithelial cell tumours, specifically nasopharyngeal carcinoma and EBV-positive gastric carcinoma, is less clear and is currently considered to be a consequence of the aberrant establishment of virus latency in epithelial cells displaying pre-malignant genetic changes. Although the precise role of EBV in the carcinogenic process is currently poorly understood, the presence of the virus in all tumour cells provides opportunities for the development of novel therapeutic and diagnostic approaches. The study of EBV and its role in carcinomas continues to provide insights into the carcinogenic process that are relevant to a broader understanding of tumour pathogenesis and to the development of targeted cancer therapies.