Several plants synthesize a chemical substances which may exhibit antifungal properties and therefore which may be of interest in crop protection. The use of these natural substances may be complementary to synthetic fungicides which are dangerous on the environment and on the consumer health. Therefore, a research of the natural substances that exhibit an effective antifungal properties is gaining great interest. The purpose of this research work has been to select vegetable materials from which to obtain leaf extracts (or essential oils) with antifungal activity, by means of an innovative process of extraction in a pilot plant that utilises a supercritical carbon dioxide, for their use in crop protection. The leaves of three species of Mediterranean plants: olive (Olea europaea L.), sweet orange (Citrus sinensis Osbeck) and laurel (Laurus nobilis L.) have been considered in this research work. Antifungal activity tests were carried out in vitro on seven strains of plant pathogenic fungi cultivated in Petri plates and each extract (or essential oil) was tested at three different concentrations (50, 125 and 250 μg/ml). The results has been demonstrated that the greatest antifungal activity was observed for the extract obtained from L. nobilis against the fungus Botrytis cinerea Pers. when it was applied at an concentration of 250 μg/ml.