ABSTRACT. Pythium spp. were isolated from symptomatic plants and agricultural soils in Uruguay. Species were identified and the pathogenicity of representative isolates was assessed in vitro on lotus, alfalfa and soybean seeds. Pythium sylvaticum and P. paroecandrum were the least virulent on lotus and alfalfa, while P. irregulare, P. ultimum and P. cryptoirregulare were the most virulent. Soybean seeds were equally affected by isolates of all tested Pythium species. @ Australasian Plant Pathology Society Inc. 2017