Geographic isolation and relatively recent arrivals of agricultural materials from the rest of the world have given Australia, New Zealand and Papua New Guinea a plant-associated nematode fauna substantially different from other countries. Although many of the major cosmopolitan species of plant-pathogenic nematodes are now present, several remain absent, particularly those with more restricted host, geographic or ecological ranges. There is a substantial indigenous plant-feeding native fauna associated with the native vegetation, but this is concentrated in a few families and genera, and few native species have become pathogenic to recently introduced commercial crops. Grasslands of both native and introduced species, as well as coastal habitats (dunes, beaches and mangroves) have been widely studied. Many plant-feeding and free-living nematodes from these habitats are from cosmopolitan taxa, but there are also endemic species and genera. Notable are the many species from otherwise terrestrial taxa in the coastal habitats. Geographic isolation has played a substantial role in evolution and radiation of many of the new taxa, as well as perhaps in the lack of many plant-parasitic nematode taxa.