The present invention relates to antifouling compositions and particularly to compositions which are able to provide an improved protecting effect against fouling organisms. More particularly, the present invention relates to synergistic antifouling compositions comprising an amount of at least 3.5 wt %, based on the total weight of the dry mass of the composition, of 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile, or a salt thereof, together with another biocide selected from bethoxazin, tolylfluanide, dichlofluanide, or DCOIT; for protecting materials against fouling organisms. This invention thus relates to the field of protection of materials, such as underwater objects, protection of wood, wood products, biodegradable materials and coatings.