Abstract: The invasive garden ant, Lasius neglectus Van Loon, Boomsma & ANDRÁSFALVY, 1990, possibly native to Asia Minor, is currently spreading through urban areas of Europe and Middle Asia. In June 2008, we discovered three populations of L. neglectus in Rostock, Germany (54.1° N, 12.1° E), the most northern location recorded for this species. The main Rostock population covers more than seven hectares, centering on an urban park. Two much smaller populations occur in a botanical garden 1.5 km to the west. Near the centre of the main population, we found no other ant species present. It is unclear how much farther north this species will spread.