The global decline of amphibians responds to multiple factors which frequently act in synergy. These factors may be categorised into two umbrella groups according to the nature of the agents implicated: abiotic (non-living) and biotic (living). The abiotic factors produce environmental changes at two different scales. At the global scale increases in ultraviolet radiation, desertification and acid rain affect the lifecycles of amphibians, affecting reproduction, destroying clutches and contaminating the environment. At the local scale the direct action of man alters and destroys habitats, especially sites of preproduction, leaving them to survive uniquely in protected areas. On the other hand some living organisms are also responsible for the general decline of amphibians. Many introduced species (fish and crabs) are present in almost all the corners of the world, predating upon and competing with indigenous amphibians, displacing them to suboptimum sites or causing them to disappear. However of far greater concern is the recent appearance of diseases specific to amphibians. These diseases are caused by a fungus and virus, recently discovered and found globally, even affecting populations in protected areas. The diseases produce mass mortalities which may lead to the extinction of populations and species. Since we do not know the origin of these diseases the unique action we can take to stop them is to avoid their dispersion and to attempt to understand why they have recently emerged.