The taxonomy of Petrogale has been in a state of flux for many years. The eight chromosome races of the eastern Petrogale radiation are currently placed in four species. However, several of these 'species' contain chromosomally unrelated taxa. In this paper a species definition for Petrogale is proposed that allows for some gene flow between species but requires a species to maintain a substantial and distinct genetic identity. When this definition was applied to the eastern Petrogale eight 'good' species were identified. Thus we now consider the eastern Petrogale complex to consist of P. penicillata, P. herberti (formerly P. penicillata herberti), P. inornata, P. assimilis, P. sharmani, sp. nov. (formerly the Mt Claro race), P. mareeba, sp. nov. (formerly the Mareeba race), P. godmani and P. coenensis, sp. nov. (formerly the Cape York race). Several of these taxa are cryptic species and the primary means of identification used was chromosome number and morphology. However, genic data were useful in establishing whether each taxon should be regarded as a separate species.