The distributions of the introduced nematode parasite, Angiostrongylus cantonensis, and the native Angiostrongylus mackerrasae in Australia are poorly understood. We sampled rodents and/or their faeces, and intermediate gastropod hosts for the presence of Angiostrongylus species in coastal forests surrounding Jervis Bay in south-eastern Australia. We found A. cantonensis in populations of introduced Rattus rattus in forests to the north of Jervis Bay, and A. mackerrasae in native Rattus fuscipes in forests to the south of Jervis Bay. The apparent geographical separation of these lungworm species may be a consequence of host specificity and negative associations between R. rattus and R. fuscipes that results from interspecific competition. A. cantonensis was regularly found in R. rattus or their faeces across 9 of 12 study sites north of Jervis Bay, and three species of snail common to the area were suitable intermediate hosts. This has potential negative implications for native wildlife and human visitors to these forests, because A. cantonensis infection causes zoonotic disease (neuro-angiostrongyliasis) in humans and a wide range of bird and mammal hosts. Management of pest rodents in the study area is warranted.