Biogeographic patterns of obligate freshwater fishes of Australia were investigated using museum records. Similarity indices, parsimony analysis, and drainage-based plots of speciesí ranges were used to identify patterns. Relationships a mong regions were deduced largely by concordance between methodologies, which were then summarized into a series of faunal provinces. The most striking pattern was the incidence of endemism across the continent. Provinces in southern, central, and weste rn Australia have high numbers of endemic fishes, presumably as a result of isolation by aridity and drainage divides. With the exception of one region, northern and eastern Australia provinces have few endemics. In the north, this may be explained by h igh drainage connectivity during times of lowered sea levels. This explanation does not account for low endemism in the east since drainages appear to have been isolated even during lowered sea levels and faunal patterns suggest an absence of distinct ba rriers of other kinds. By default, climate again seems the most likely cause of speciesí distributional limits. Whatever the case, most patterns seem to have been established in the distant past, perhaps as early as Miocene; influences of Plio-Pleistoce ne events on broader patterns of freshwater fish distributions seem to have been minimal.