Technical Abstract: The current ICTV report lists 2284 virus and viroid species distributed amongst 349 genera, 19 subfamilies, 87 families and 6 orders. There is also a chapter of unassigned viruses that provides information on a number of viruses that have not yet been classified but are probably representatives of new genera and/or families. The final chapters describe the satellites (and other virus-dependent nucleic acids) and prions (which include the agents of spongiform encephalopathies of humans), which are not formally classified by ICTV but simply listed for historical reasons. The Ninth Report is being published both as a book and also online. ICTV expects to make regular updates to keep the online version in step with the latest taxonomic decisions. The Closteroviridae chapter covers updates in taxonomy within this family, highlights the characteristics that delineate genera in the family and lists species that have not been assigned to a genus. There are three recognized genera in the family; the closteroviruses that are monopartite and transmitted by aphids, the ampeloviruses that are monopartite and transmitted by mealybugs and the criniviruses that are whitefly transmitted with one species that is tripartite.