The article provides a summary of the results from the International Committee on Taxonomy of Viruses (ICTV) meeting held in Madrid in September 1975. Key points include: 1. **Nomenclature Rules**: Minor and major changes were approved, particularly regarding Rule 4 (effort towards Latinized binomial nomenclature) and Rule 7 (new sigla not to be introduced). The rules now allow for the use of meaningful sigla if recommended by international virus study groups. 2. **Executive Committee Composition**: New members were elected, including Professor R. E. F. Matthews as President, Dr. H. G. Pereira as Vice-President, and several other virologists. 3. **Viruses of Interest to Different Groups**: - **Vertebrate Virologists**: Focus on viruses causing diseases in humans and domestic animals, with some viruses found in invertebrates and plants. - **Plant Virologists**: Study viruses affecting plants, with 12 named subgroups proposed, three of which were approved. New groups like Closterovirus and Hordeivirus were also approved. - **Invertebrate Virologists**: Despite invertebrates being prevalent, research is limited. Some viruses found in invertebrates may belong to families already characterized in vertebrates or plants. - **Bacterial Virologists**: Molecular biology has advanced significantly in this field, but comparative studies are limited. The Bacterial Virus Subcommittee proposed several families and genera, but no definitive names were approved at the meeting. 4. **New Families and Genera**: Several new families and genera were proposed, including Myoviridae, Styloviridae, and Pedoviridae, among others, to better categorize and understand the diversity of viral infections. The article aims to provide an up-to-date overview of viral taxonomy and nomenclature, ensuring that virologists have access to the latest information.The article provides a summary of the results from the International Committee on Taxonomy of Viruses (ICTV) meeting held in Madrid in September 1975. Key points include: 1. **Nomenclature Rules**: Minor and major changes were approved, particularly regarding Rule 4 (effort towards Latinized binomial nomenclature) and Rule 7 (new sigla not to be introduced). The rules now allow for the use of meaningful sigla if recommended by international virus study groups. 2. **Executive Committee Composition**: New members were elected, including Professor R. E. F. Matthews as President, Dr. H. G. Pereira as Vice-President, and several other virologists. 3. **Viruses of Interest to Different Groups**: - **Vertebrate Virologists**: Focus on viruses causing diseases in humans and domestic animals, with some viruses found in invertebrates and plants. - **Plant Virologists**: Study viruses affecting plants, with 12 named subgroups proposed, three of which were approved. New groups like Closterovirus and Hordeivirus were also approved. - **Invertebrate Virologists**: Despite invertebrates being prevalent, research is limited. Some viruses found in invertebrates may belong to families already characterized in vertebrates or plants. - **Bacterial Virologists**: Molecular biology has advanced significantly in this field, but comparative studies are limited. The Bacterial Virus Subcommittee proposed several families and genera, but no definitive names were approved at the meeting. 4. **New Families and Genera**: Several new families and genera were proposed, including Myoviridae, Styloviridae, and Pedoviridae, among others, to better categorize and understand the diversity of viral infections. The article aims to provide an up-to-date overview of viral taxonomy and nomenclature, ensuring that virologists have access to the latest information.