The history of pestivirus taxonomy is surprisingly consistent: almost 30 years ago it was recognized that pestiviruses are structurally akin to flaviviruses, and recent nucleotide sequence data have confirmed this resemblance at the level of genome organization. For other enveloped positive stranded RNA viruses with ikosahedral nucleocapsids e.g. equine arteritis and lactate dehydrogenase virus of mice a taxonomic dilemma is encountered; while virions resemble ("non-arthropod-borne") togaviruses, the replication via a nested set of subgenomic RNAs is corona and torovirus-like. Pestiviruses, flaviviruses and the hepatitis C virus group have been assigned generic status in the Flaviviridae family.