The Atlantic Forest contains more than 20,000 species of plants, including rare palms, orchids and bromeliads, and is recognized as one of the world's locations with the greatest tree diversity. In the south of the state of Bahia, scientists from the New York Botanical Gardens have found 458 different tree species within a single hectare - that is more than can be found on the entire eastern seaboard of the United States. Furthermore, the Atlantic Forest is home to 2,180 species of vertebrates - mammals, amphibians, reptiles, fish and birds. More than 800 of these species are endemic to the Atlantic Forest, in other words, do not occur in any other place. Due to the considerable threat facing this biome, 60% of Brazil's endangered species are to be found in the Atlantic Forest.

The diversity of the vertebrates and the level of endemism in the forest are extremely high. The Atlantic Forest has 12 endemic genera, meaning species that are not found anywhere else on Earth, including two genera of endangered primates that symbolize and are identified with the region: the lion tamarins, of which there are four species, and the spider monkeys, of which there are two species. The conservation efforts to save the lion tamarins have demonstrated the importance of cooperation between universities, zoos, domestic and international NGOs and the Brazilian government, which has led not only to their protection, but also to the preservation of their forests. The conservation and research activities focused on these species have resulted in the development of numerous initiatives aimed at protecting the habitat of these primates, as well as the training of a large number of Brazilian conservationists.