in vitro- and in vivo-assays were conducted, to study the possible role of streptomycin- and actinomycin-producing soil actinomycetes for the pathogenesis of "cara inchada" in cattle (ci). adherence of bacteroides spp. to epithelial cells of the bovine gingiva, known to be associated with the progressive lesions of ci, was significantly increased by the addition of streptomycin, actinomycin or antibiotic culture supernatants of the soil actinomycetes. applications of these mixtures together with actinomyces pyogenes to the marginal gingiva of the upper premolar teeth of about 1 month old holstein friesian calves did not lead to progressive lesions of ci. only one calf exhibited a slight diarrhea and a temporary retraction of the gingiva at the site of application.