This article presents a report "IVth Meeting of the International Council for the Study of Viruses and Virus Diseases of Grapevine, Colmar," by Institut National de la Recherche Agronomique. This report of the 4th symposium on viruses attacking the grapevine provides an up-to-date review of the present problems and also includes paper on several diseases probably caused by mycoplasms. The increasing importance of clonal breeding of vines makes it doubly important that virus-free stocks are used.