Large collections of Syllidae (Polychaeta) from around Australia, housed at the Australian Museum (Sydney), have been examined and identified. Australian material from the Hamburgische Zoologische Museum der Universität, Hamburg, Germany was also examined. All known Australian species of the subfamily Eusyllinae (Syllidae) are described and figured. Some were examined using the Scanning Electron Microscope to illustrate characters and methods of reproduction in this subfamily. Keys to genera and species are given. A total of 53 species are reported from Australia belonging to 14 genera: Amblyosyllis Grube, 1857 (3 species); Anoplosyllis Claparède, 1868 (1 species); Astreptosyllis Kudenov & Dorsey, 1982 (2 species); Eusyllis Malmgren, 1867 (3 species); Nudisyllis Knox & Cameron, 1970 (1 species); Odontosyllis Claparède, 1863 (9 species); Opisthodonta Langerhans, 1879 (3 species); Paraehlersia San Martín, 2003 (2 species); Paraopisthosyllis Hartmann-Schröder, 1991 (4 species); Pionosyllis Malmgren, 1867 (15 species); Psammosyllis Westheide, 1990 (1 species); Streptodonta n.gen. (1 species); Streptosyllis Webster & Benedict, 1884 (3 species); and Syllides Örsted, 1845 (5 species). A total of 15 new species are described: Amblyosyllis enigmatica, A. multidenticulata, Odontosyllis marombibooral; Opisthodonta hanneloreae, Paraopisthosyllis alternocirra, P. ornaticirra, Syllides tam, Pionosyllis rousei, P. kalimna, P. yolandae, P. mariae, P. mayteae, P. ancori, P. koolalya, and P. heterochaetosa. A new name, Pionosyllis hartmannschroederae, is proposed for Typosyllis (Langerhansia) longisetosa Hartmann-Schröder, 1990 as this is junior homonym of Pionosyllis longisetosa (Hartmann-Schröder, 1965). Additionally, five species are new records for Australia: Odontosyllis gravelyi Fauvel, 1930; Opisthodonta morena Langerhans, 1879; Pionosyllis corallicola Ding & Westheide, 1997; Streptodonta pterochaeta (Southern, 1914) and Syllides japonicus Imajima, 1966. A discussion of the reproduction and systematics of the subfamily is given.