AbstractBackground Oral hairy leukoplakia (OHL) is a greyish white keratotic lesion occurring unilaterally or bilaterally on the lateral border or ventral surface of the tongue and occasionally at other mucosal sites. This lesion is seen in immunosuppressed individuals, usually in association with HIV infection.Aims The clinical and histopathological features of OHL are only sufficient to reach a presumptive diagnosis. Definitive diagnosis of OHL requires demonstration of the presence of Epstein‐Barr virus (EBV) within the OHL lesion. Prompt and accurate recognition of the condition is important, as it is an early and reliable sign of infection with human immunodeficiency virus (HIV).Conclusions A definitive diagnosis of OHL may be acheived by detection of EBV in the lesion through the use of immunohistochemistry or in situ hybridisation on biopsy material.