ABSTRACTThe taxonomy, diversity and conservation status of all species of the family Pottiaceae in the Atlantic Rainforest of Rio de Janeiro State in southeastern Brazil are presented. The Atlantic Rainforest is a globally recognized biodiversity hotspot. The treatments are based on field expeditions and studies of herbarium collections. Twenty eight species from 18 genera are discussed. A key to the genera and species is provided, with comments on their distributions and altitudinal ranges, with illustrations and evaluation of the conservation status.