Bioassay-guided chromatographic separation of the cytotoxic MeOH extract of Phaius mishmensis led to the isolation of two known and six new indoloquinazolinones, phaitanthrins A-E (1-5) and methylisatoid (6). The structures of the new compounds were elucidated by spectroscopic analysis. Phaitanthrin A (1) and tryptanthrin (7) showed moderate cytotoxicity against MCF-7, NCI-H460, and SF-268 cell lines