Epstein-Barr virus is associated with many diseases. Today, the pathologist may study either by immunohistochemistry or in situ hybridization on tissue sections: EBV genome, EBV messenger RNA, EBV latent and replicative proteins. Several technics can be performed on fixed paraffin-embedded tissue to demonstrate the presence of EBV DNA, EBER-1 RNA, LMP-1 protein. Frozen tissues are required for the study of EBNA-2, ZEBRA and replicating proteins expression. The results, obtained during the study of benign and malignant proliferations always or often associated with EBV, such as infectious mononucleosis, Burkitt's lymphomas, AIDS associated lymphomas, lymphoproliferations in immunocompromised patients, Hodgkin's disease, and some epithelial proliferations, are summarized.