This disease card published by the World Organisation for Animal Health (OIE) provides information about tilapia lake virus (TiLV), a recently observed pathogen causing significant mortalities in cultured tilapia. The disease card provides details of the pathogen, modes of transmission, host range, geographical distribution, clinical signs, diagnostic methods, socio-economic significance, transmission risk and a list of available references. We urge laboratories to test for TiLV when abnormal tilapia mortalities occur.