This paper indicates the present and the potential value of the Ostracoda in Queensland Tertiary stratigraphy. The ostracods contained in samples from eight boreholes in The Narrows Tertiary basin are described, and shown to be of value in enabling a zonation and approximate correlation of the strata to be drawn up. Ostracods from the Petrie Series and the Baffle Creek Tertiaries are also described, and the faunas compared with those of The Narrows Tertiaries and the Redbank Plains Series. As the result of this work, a probable Miocene age is suggested for both The Narrows Tertiaries and the Petrie Series, and a probable Oligocene age for the Baffle Creek Tertiaries and the Redbank Plains Series. The environmental conditions of deposition and origin of the ostracod-bearing shales in these basins, together with other related data, are discussed.