Abstract: An ecologically compatible anti-microbial-adhesion agent is described, which is particularly suitable for use in anti-fouling paints, preferably for boats, characterized in that it comprises a compound selected from eugenol, vanillin, benzaldehyde substituted with one or two substituents selected from the groups —OH (hydroxy) and —OCH3 (methoxy), or any combination thereof. An anti-fouling paint is also described, particularly for boats, comprising the anti-microbial-adhesion agent mentioned above and other components selected from conventional biocides, solvents, resins, pigments, charges and fillings, and combinations thereof.