As part of the vegetation analysis of the Interior Columbia River Basin Ecosystem Management Project, the bryophyte (liverwort, hornwort and moss) flora was investigate. The study area included the Columbia River Basin south of the Canadian border, part of the northern Great Basin, and part of the upper Klamath River watershed. The Cascade Range and northern Rocky Mountains are relatively well known bryologically, but the intermountain region is poorly known. Traditionally, these components of the basin have been treated separately south of the Canadian border, and usually separately by state. This project presented an excellent opportunity to collate information and treat the bryoflora of the Columbia basin as a cohesive floristic unit. The objectives of this project were to identify (1) what species are known to occur in the study area, (2) where they occur, (3) their role in the ecosystem, (4) rare species or habitats in need of special management, and (5) aspects of the regional bryoflora needing further investigation.