The state of Rio de Janeiro is characterized by high biological diversity due to its location with an assortment of geographical formations and habitats. The region has a high level of endemism. The aim of this study was to provide data on the conservation priorities for the bryophytes of Rio de Janeiro using the information contained in a database that incorporated both specimens from the RB herbarium and existing literature. Maps were prepared showing bryophyte richness, including endemic, vulnerable and threatened species, species richness within individual conservation units, and the conservation priorities for the bryophytes within the state of Rio de Janeiro. The bryophytes of Rio de Janeiro are estimated at 1040 species, about 33% of all known Brazilian species. Most of the previous inventories have focused on the montane rainforest and coastal region. One hundred and fifty species (14%) are considered 'vulnerable' or 'threatened' on a regional scale. Although more data are required, this analysis provides important information on the composition, distribution, and status of threatened bryophytes of Rio de Janeiro. The high number of species considered to belong to the 'data deficient' category made analysis difficult and emphasizes the need for further studies. Among the most important habitats for conservation action are the remnants of old-growth Atlantic rainforests. The major threat to the bryoflora is the reduction, fragmentation, and isolation of this important forest ecosystem. The total protected area in Rio de Janeiro state amounts to almost 13% of the total land area of the state and most of this area consists of montane and upper montane Atlantic rainforests.
