I: Introduction to the Universal System of Virus Taxonomy.- The History of Virus Taxonomy.- The International Committee on Taxonomy of Viruses (ICTV).- The Universal System of Virus Taxonomy.- Virus Nomenclature.- Structural, Genomic, Physicochemical and Replicative Properties of Viruses Used in Taxonomy.- Some Properties of Viruses Used in Taxonomy.- Taxonomy and Unambiguous Virus Identification.- Taxonomy and the Adequate Description of New Viruses.- Taxonomy in Diagnostic Virology.- The Future of Virus Taxonomy.- II: The Viruses.- Glossary of Abbreviations and Virological Terms.- Virus Diagrams.- Taxa Listed Alphabetically.- Taxa Listed by Host.- Taxa Listed by Nucleic Acid.- Key to the Placement of Viruses in Taxa.- The Order of Presentation of the Viruses.- Descriptions of Taxa.- III: The International Committee on Taxonomy of Viruses.- Officers and Members of the ICTV, 1990-1993.- The Statutes of the ICTV, 1993.- The Rules of Virus Classification and Nomenclature, 1993.- The Format for Submission of New Taxonomic Proposals.- IV: Indexes.- Author Index.- Virus Index.- Taxonomic Index.