Technical Abstract: The ascomycete fungus Eutypa lata is a trunk pathogen of cultivated grapevine (Vitis vinifera) in all major grape-growing regions of the world. Throughout its geographic range, it is considered a generalist pathogen that can complete its life cycle on a broad range of hosts. To decipher the cosmopolitan distribution of this fungus, we investigated the population genetic structure of 19 geographic samples from four continental regions (Australia, California, South Africa and Europe), based on analyses of 287 isolates genotyped with nine microsatellite markers. High levels of genotypic diversity and absence of multilocus linkage disequilibrium among loci supported the preponderance of sexual reproduction in all regions examined. Nonetheless, the identification of identical multilocus haplotypes with identical vegetative compatibility groups, in vineyards in California and South Africa, suggests that dispersal of asexual spores of the fungus could be a rare means of disease spread. The greatest levels of allelic richness and gene diversity were found in Europe, among geographic samples from coastal areas surrounding the Mediterranean Sea, whereas the lowest genetic diversity was found in South Africa. Samples from California, Australia and South Africa, which had lower genetic diversity than those of Europe, were also characterized by demographic disequilibrium and, thus, may represent founding populations of the pathogen. Low levels of genetic differentiation among all samples suggest that gene flow prevents differentiation at continental scales. These findings suggest that global, human-mediated spread of the fungus may have resulted in its currently global distribution.