The archipelago of Fernando de Noronha (FN) is located about 350km of the northeast coast of Brazil and is recognized as a UNESCO World Heritage site for the importance of the marine environment. Island environments are unique with many endemic species and compared to the continent there is greater vulnerability of species and habitats to threats. For Brazilian oceanic islands, invasive species and habitat loss are leading short-term threats to biodiversity. On FN, the current fauna of terrestrial vertebrates is mostly composed of introduced species including the Cururu Toad (Rhinella jimi). Previous work showed a high prevalence of toads on FN with limb and eye malformations and limited surveys demonstrated evidence of underlying disease problems (e.g. mycobacteriosis). To better define the extent of malformations and disease, we randomly collected and . examined 100 adult toads and collected samples for histopathology. microbiology, parasitology and radiology. Apparent anomalies were found in 45 animals with 84.4% affected the limbs (e.g. short, missing or fused digits) and 11. 1 % affecting the eyes (e.g. microphthalmia or pththis bulbii). Radiology and histopathology suggests some anomalies are not developmental, but instead were caused by trauma (e.g. fractures) or infectious diseases (e.g, osteomyelitis or panopthalmitis). Twenty-nine percent of the animals had granulomas in the liver, spleen and kidney with intralesional acid-fast bacteria. A Mycobacterium marinum-type organism was isolated from most of these cases. A small number of animals had a protozoan parasite in the brain with morphologic similarities to both Toxoplasma gondii or Cystodiscus sp. (identification pending) . The health alterations presented by these toads, introduced in an altered habitat, suggests that they can become useful as a model for ecosystem health monitoring for endemic wildlife species on FN.