The antifungal activity of nine plant extracts manufactured by Hofigal Import Export S.A. Romania against the biocontrol fungal agent Trichoderma viride Pers. (isolate Tv 82) was assessed in vitro for the first time in Romania. In general, the development (mycelial growth and sporulation) was not inhibited by the six plant extracts (Satureja hortensis, Achillea millefolium, Allium sativum, Mentha sp., Hyssopus officinalis, Artemisia dracunculus 'Sativa'), with three exceptions (Rosmarinus officinalis, Valeriana officinalis, Tagetes patula), applied in a concentration of 20%. Among these, the extract of Tagetes patula has inhibited the Tv 82 development, applied as lower concentrations (10% and 5%), efficacy being 54.3% and 50%, respectively. In addition, the tested plant extracts of Satureja hortensis, Achillea millefolium, Mentha sp. proved stimulative effect on Tv 82 development. This approach add to the early studies on the selectivity of Trichoderma spp. to chemicals used in plant protection, new data referring to the use of antagonistic fungi, like Trichoderma spp., as a protective mean against phytopathogens. Also, these data sustain the possibility of applying plant extracts as an alternative in plant protection or to apply together chemical (pesticides) and biological means (plant extracts) especially to protect ecological crops, as vegetables, medicinal plants a.o.