Chromatographic separation of a methanol extract prepared from the whole plant of Dendrobium brymerianum led to the isolation of eight phenolic compounds. Among the isolated compounds (1-8), moscatilin (1), gigantol (3), lusianthridin (4), and dendroflorin (6) showed appreciable cytotoxicity against human lung cancer cell lines with IC50 values of 196.7, 23.4, 65.0, and 125.8 μg/mL, respectively, and exhibited antimigratory property at nontoxic concentrations. This study is the first report on the biological activities of this plant.