Abstract: Verticillium longisporum is an amphidiploid fungal pathogen specialized on Brassicaceae hosts of which three genetically different lineages have been found so far in the field. Previous studies have shown that the lineages of V. longisporum differ in their frequency, occurrence, distribution, and host preferences. To further investigate the distribution of lineages in European oilseed rape fields, we carried out, for the first time, a large scale V. longisporum lineage monitoring with stubble samples collected during four years (2013-2016) from 52 locations in seven European countries, which resulted in a total of 306 isolates. Using a Multiplex-PCR, all isolates were assigned to the lineage A1/D1. The broad temporal and geographic scope of this monitoring demonstrates a dominant role of lineage A1/D1 in European oilseed rape fields. To further investigate whether genetic subpopulations exist within the lineage A1/D1 with different pathogenic traits, a selection of 96 isolates will be genetically characterized with genotyping by sequencing (GBS) for a further in-depth study of genetic diversity.