This paper reviews the factors involved in the decline, both inter- and intra-specific, of Australian frogs from both disturbed and apparently pristine habitats. Despite a lack of published accounts and an absence of long term population studies, a variety of causes were identified. Habitat changes, owing to human influences, are lowering frog numbers and species diversity. Other factors involved include heavy metals, pesticides, salinity, temperature, disease, competition from introduced species and human collection. The complex interactions and synergistic effects of these factors on frogs have yet to be fully elucidated. However, since frogs are sensitive to environmental influences at all stages of their life cycle, population studies would provide base line data to identify, at an early stage, the impact of human influence.