Seven species of Syllidae (Annelida, Polychaeta) inhabiting colonies of the bryozoan Schizoporella unicornis (Johnston), a common species on the beaches of Ubatuba and São Sebastião, São Paulo State, Brazil are described: Exogone occidentalis Westheide, 1974; Haplosyllis spongicola (Grube, 1855); Opistosyllis corallicola Hartmann-Schröder, 1965; Syllis gracilis (Grube, 1840); Trypanosyllis taeniaformis (Haswell, 1866); Typosyllis maculata Imajima, 1966 and Typosyllis variegata (Grube, 1860). Among these, E. occidentalis, O. corallicola, T. taeniaformis and T. maculata are cited for the first time for the Brazilian coast. The most abundant of these species was S. gracilis.