Based on published and unpublished material the present study represents the first comprehensive work covering all scale worms (Aphroditoidea) currently known to occur in the Mediterranean Sea. In total 66 species representing 38 genera are confirmed, described, and figured in detail and taxonomical problems discussed. The aphroditoidean fauna of the Mediterranean Sea comprises the following confirmed numbers of species: 41 Polynoidae, 11 Sigalionidae, 5 Aphroditidae, 5 Acoetidae, 2 Eulepethidae, and 2 Pholoidae. Identification keys to all species occurring in the Mediterranean and to those of the East Atlantic and the northern part of the Red Sea are provided. In the course of this study three new species, i.e. Harmothoe bellani Barnich & Fiege, 2000, Malmgreniella polypapillata Barnich & Fiege, 2001, Eunoe sp. nov., and a new genus, Neolagisca Barnich & Fiege, 2000 are described and 17 new records of species formerly known from the Atlantic and the Red Sea are reported. Together these two groups represent 30.3 % of the species present. The aphroditoidean fauna of the Mediterranean is closely related to the Eastern Atlantic fauna with 56 species (84.8 %) in common. Four species (6.1 %) occur also in the Red Sea with two of them being likely Lessepsian migrants, representing the first recorded among scale worms. Only six species (9.1 %) of Aphroditoidea have to be considered endemic to the Mediterranean for the time being, thus representing a much lower number than those reported for many other taxa. Among the Atlantic species present in the Mediterranean a decline in species numbers is observed from the Western to the Eastern Mediterranean with 14 species (20 %) missing in the Eastern Mediterranean. Besides less favorable ecological conditions, the lack of material available from this area are discussed. The depth distribution of the species is analysed resulting in a low number of true deep-sea species.