Sessile organisms can use physical, chemical, and biological mecanisms to control, avoid or induce epibiosis. The antifouling capacity of crude organic extracts from the marine sponges Cribrochalina infundibulum (=C. vasculum) and Biemna cribaria, was evaluated. Natural concentrations of sponges extracts were added to agar based gels and deployed in the field during 28 days, to offer substrate to natural epibiotic community. Colonization extent was then compared with control gels without extracts. Extracts from both sponges significatively inhibited the colonization of most of epifaunal organisms. B. cribaria was found to be more effective than C. infundibulum; moreover its extract lixivation was lower with a longer inhibitory action.