ABSTRACT. – Serpulids associated with the Cystoseira brachycarpa, C. sauvageauana and C. spinosa communities from 5, 10 and 25 m water depth, respectively, along the eastern coast of Sicily, in the Ionian Sea (Mediterranean), have been studied. A total of 19 species were found including 13 serpulins and 6 spirorbins colonizing a few soft algal species offering large, relatively consistent and persistent substrata, as well as coralline thalli and lithic granules. Although represented by a fewer number of species, spirorbins are by far more abundant than serpulins in specimen number, above all in the two shallowest communities, which are less diversified. The composition and structure of assemblages seem to be shaped by general environmental conditions (mostly light/shadowing) and the presence, morphology and persistence of algal species suitable to be colonized, also in relation to hydrodynamic energy.