The Epstein-Barr virus (EBV) was discovered in 1964 by Michael Anthony Epstein and Yvonne Barr, who discovered a herpesvirus-like infectious agent in a biopsy specimen from a patient with Burkitt's lymphoma. This virus belongs to the Herpesviridae family (subfamily Gammaherpesvirinae, genus Lymphocryptovirus). EBV is a ubiquitous herpesvirus that is causally associated with various malignant tumours. According to the current nomenclature, it was named human herpesvirus type 4 (human herpesvirus 4 - HHV-4). Primary infection usually occurs in childhood. In developing countries, the infection rate among young children is higher than in developed countries. It was the first human tumour virus and it is currently categorized as a group-1 carcinogen due to its association with various cancers. It is estimated that over 90% of the adult population has been infected with this pathogen, but only a minority will develop the disease. EBV establishes latent infection characterized by the expression of a limited number of viral genes called latent genes. Moreover, during its life cycle, EBV periodically reactivates and can be transmitted to other susceptible hosts. The oral cavity is the main site of EBV occurrence and the most common source of infection. This study discusses EBV frequency and its association with the occurrence of malignant tumours and the pathways of tumour progression.