Rumex obtusifoliusis a problematic weed in temperate grasslands worldwide as it decreases yield and nutritional value of forage. Because the species can recruit from the seed bank, we determined the effect of management and soil properties on the soil seed bank ofR.obtusifoliusin intensively managed, permanent grasslands in Switzerland (CH), Slovenia (SI), and United Kingdom (UK). Following a paired case-control design, soil cores were taken from the topsoil of grassland with a high density ofR.obtusifoliusplants (cases) and from nearby parcels with very lowR.obtusifoliusdensity (controls). Data on grassland management, soil nutrients, pH, soil texture, and density ofR.obtusifoliusplants were also collected. Seeds in the soil were germinated under optimal conditions in a glasshouse. The number of germinated seeds ofR.obtusifoliusin case parcels was 866 ±152 m-2(CH, mean ±SE), 628 ±183 m-2(SI), and 752 ±183 m-2(UK), with no significant difference among countries. Densities in individual case parcels ranged from 0 up to approximately 3000 seeds m-2(each country). Control parcels had significantly fewer seeds, with a mean of 51 ±18, 75 ±52, and 98 ±52 seeds m-2in CH, SI, and UK, respectively, and a range between 0 and up to 1000 seeds m-2. Across countries, variables explaining variation in the soil seed bank ofR.obtusifoliusin case parcels were soil pH (negative relation), silt content (negative), land-use intensity (negative), and abovegroundR.obtusifoliusplant density (positive). Because a large soil seed bank can sustain grassland infestation withR.obtusifolius, management strategies to control the species should target the reduction in the density of mature plants, prevention of the species’ seed production and dispersal, as well as the regulation of the soil pH to a range optimal for forage production.