A new bixanthone derivative, garciobioxanthone (1), was isolated from the EtOH extract of the bark of Garcinia oblongifolia, together with 11 known compounds. The structure of 1 was elucidated on the basis of 1D NMR, 2D NMR and other spectroscopic analysis. The structures of the known compounds were identified by comparison of their spectroscopic data with those reported in the references.