Acute retinal necrosis (ARN) is a relatively rare syndrome that is caused by infection with one of several members of the human herpesvirus family. ARN usually occurs in otherwise healthy patients, although it has also been observed in immunocompromised individuals. It is characterized by retinal vasculitis and haemorrhaging, areas of retinal necrosis, vitreous and aqueous inflammation and optic neuritis. It may affect one or both eyes and frequently results in severely reduced vision or blindness in the affected eye. Results using the mouse model of ARN have provided insight into the pathogenesis of this disease. However, many unanswered questions remain, such as why does only a very small fraction of individuals infected with one or more herpesvirus develop ARN? Increased understanding of the interactions of herpesviruses with T cells and cytokines may enable the development of therapeutic strategies targeted specifically to control viral infection in the eye and/or brain.