The family Scaridae is represented on the tropical and subtropical coasts of eastern Australia by 25 previously described species. Three species belong in the subfamily Sparisomatinae: Leptoscarus vaigiensis (Quoy & Gaimard); Calotomus earolinus (Valenciennes); Calotomus spinidens (Quoy & Gaimard). The remainder are included in the subfamily Scarinae: Bolbometopon murieatum (Valenciennes); Cetoscarus bieolor (Rüppell); Hipposcarus longiceps (Valenciennes); Scarus altipinnis (Steindachner); Scarus bleekeri (de Beaufort); Scarus dimidiatus Bleeker; Scarus flavipectoralis Schultz; Scarus forsteni (Bleeker); Scarus frenatus Lacepede; Scarus frontalis Valenciennes; Scarus ghobban Forsskål; Scarus gibbus Rüppell; Scarus globiceps Valenciennes; Scarus longipinnis Randall & Choat; Scarus niger Forsskål; Scarus oviceps Valenciennes; Scarus psittacus Forsskål; Scarus pyrrhurus (Jordan & Seale); Scarus rivulatus Valenciennes; Scarus rubroviolaceus Bleeker; Scarus sehlegeli (Bleeker); Scarus sordidus Forsskål; Scarus spinus Kner. The scarid from Australian waters previously misidentified as Scarus lunula (a synonym of Scarus festivus Valenciennes) represents an undescribed species Scarus chameleon, described herein. Scarus chameleon has a distribution that includes the western and southern Pacific. It is similar to S. festivus but differs in patterns of head and body colouration in the terminal phase, and in the head profile. All but three species listed above are most commonly encountered on the coral reefs of the Great Barrier Reef and the adjacent coral sea. The exceptions are the sparisomatine species Leptoscarus vaigiensis and Calotomus spinidens, and the scarinine species Scarus ghobban. The former two species are often associated with seagrass beds in coastal areas, while Scarus ghobban frequents a variety of nonreef habitats. Many of the species listed extend into northern and western Australian waters. Additional collecting is required to establish the limits and identities of the entire Australian scarid. fauna. Colour photographs of fresh specimens illustrating the different colour phases of all 27 species are provided. In addition, underwater colour photographs of most species are provided with an emphasis on those which show confusing patterns of short term variation in the initial colour phase. Illustrations of the juvenile phase are provided for some species.