Abstract: To date, the family of herpesviruses comprises important human and many veterinary relevant pathogens encompassing more than 100 herpesviruses that infect vertebrates. A common feature of herpesviruses is their ability to infect the host for life. Equine herpesvirus type 1 (EHV-1) is one of the most important causes of respiratory diseases in horses and may cause abortion and nervous manifestations (equine herpes myeloencephalopathy) with frequently fatal outcome. The present review article was aimed to through light about the etiology, epidemiology, pathogenesis and diagnosis of Equine herpesvirus type 1 infection. Epidemiology of EHV-1 included the history of the disease, distribution and prevalence of EHV-1, routes 0f transmission, risk factors and latency. Enzyme Linked Immunosorbent Assay (ELISA) and Virus Neutralization Test (VNT) are highly recommended by the Office International des Epizooties (OIE) either for EHV confirmation of clinical cases or prevalence of infection surveillance. Isolation and identification of EHV-1 from nasal or nasopharyngeal swabs or buffy coat samples are strongly supportive of diagnosis of Equine Herpes Myeloencephalopathy (EHM) in a horse with compatible clinical signs and considered as the olden standard test for a laboratory diagnosis of EHV-1 infection and should be attempted, especially during epidemics of EHM, concurrent with use of rapid diagnostic tests such as the Polymerase Chain Reaction (PCR), in order to achieve retrospective biological and molecular characterization of the viral isolate.