Abstract: Competition between micro-organisms and the production of inhibitor substances by some of these micro-organisms is frequent in substrata with varied, complex microbiota, such as cork. The main aim of this study was to determine the inhibitor activity of filamentous fungi, yeasts and bacteria isolated from wine bottle corks. The inhibitor activity of isolated micro-organisms was determined by placing disks of pure culture in Petri dishes containing 2% malt extract agar for fungi and trypticase soy agar for bacteria. These were surface-seeded beforehand with the test micro-organism, the dishes are incubated in conditions suitable for the growth of the surface-seeded micro-organisms and finally the inhibitor plaques produced are measured. The results indicate that the micro-organisms with the greatest inhibitor activity are Penicillium citrinum and Trichoderma viride.