The antifouling performance of the dogfishScyliorhinus canicula(L.) (Elasmobranchii: Squaliformes) eggcase-embryo combination was studied under experimental conditions, in conjunction with an analysis of fouling on wild cases. The cases were shown to develop an external heterogeneous microbial biofilm, and an internal heterogeneous microbial biofilm (when the case opens) composed primarily of cocci and bacilli. Macrofouling was limited on egg-cases (unless kept under high light intensities). Macrofouling ranged from <5% (recently laid cases) to 42% (>300 days exposure). This is a better performance than many commercial antifouling treatments. There was no evidence that the embryo was involved in the antifouling process.A priori, three hypotheses are suggested that might explain the antifouling mechanism of the dogfish eggcase-embryo combination: (1) the yolk/albumin/embryo emit antifouling chemicals; (2) a bacterial culture develops that prevents further fouling; (3) the case with/without an embryo has antifouling properties. The results presented here support the third hypothesis.