The Perth Basin is a narrow, elongate structure with an onshore area of some 45 000 km2, extending approximately 1000 km along the Western Australian coastline and bounded in the east by the Darling Range. Sedimentary fill ranges in age from Silurian to Modern, with Quaternary sediments attaining a maximum thickness of some 150 m. Amino acid racemization reactions are applied in assessments of the relative ages of several Quaternary marginal marine lithostratigraphic units within the Perth region. These sequences were deposited in response to four temporally distinct marine transgressions during the early, middle and late Pleistocene and the Holocene. Amino acid data indicate that Pleistocene and Holocene sequences may only be delineated using this method within increments of approximately 20 000 and 3000 years, respectively, with an effective time span serving approximately the last 600 000 years for regions presently characterized by temperate climates in Australia (MAT 18°C). The range of the technique may be significantly less for tropical settings that experience higher mean annual temperatures and as a corollary have higher ‘Effective Quaternary Temperature’ histories. The extent of racemization evident in Last Interglacial and Penultimate Interglacial molluscan fossils from the Perth region compare favourably with the same species from coastal deposits of equivalent age in South Australia and highlights the possibility of chronocorrelation of deposits from widely separated sites.