One of the major problems of the carnation crop in Colombia is the vascular wilt disease caused by Fusarium oxysporum f.. sp. dianthi (Foxd). Since the only method currently used to control andlor prevent the disease is the application offungicides, which are not as effective as expected and when used in excess causing asevere environmental damage, the alternative of using native microbiaJ populations for the control is a very interesting perspective. Among these biological agents, Trichoderma sp. and some actinomycetes have been studied due to their ability to produce substances that inhibit the growth andlor activity ofthis phytopathogen. In this study several strains of both kinds of biological agents were isolated and tested for antagonistic activity in vitro. Six Trichoderma sp strains and thirty different actinomycetes were isolated from soils of three carnation crops farms of the Bogota Plateau. Inhibition of Foxd growth was evaluated in vitro by measuring the mycelium inhibition rate (%MI) and the inhibition zone of Foxd growing in contact with the putative antagonists in fungi-fungi and fungi-actinomycete interactions. We found that al! Trichoderma sp and actinomycetes isolates exhibited an %MI greater than 50%. Isolate VI of Trichoderma sp (TVI) reached an %MI as high as 89% while isolate VII of actinomycetes (AVII, later identified as Streptomyces sp) reached an %MI of 91% with an inhibition zone greater than 1 cm. Furthermore, it was impossible to determine the associated antagonistic activity ofTVI and AVII isolates cultured together because the latter inhibited the growth of the former.