The ethanolic extract from leaves of Rauia resinosa, Rutaceae, provided a new flavone, 5-hydroxy-5',6,7-trimethoxy-3',4'-methylenedioxyflavone (1), in addition to four known compounds:3',4',5,5',7-pentamethoxyflavone (2), 5,7,8-trimethoxy-3'4'methylenedioxyflavone (3), 3',4',5,7,8-pentamethoxyflavone (4) and β-sitosterol (5).The structures of all compounds were established on the basis of spectroscopic methods, mainly 1D and 2D NMR, UPLC-DAD-MS and UPLC-ESI-MS/MS, involving comparison with literature data. Cytotoxicity of leaves and stems extracts, their fractions and compounds (2), (3), (4) and (5) were evaluated against T24 (bladder carcinoma),TOV-21-G (ovarian adenocarcinoma) and HepG2 (liver carcinoma) cell lines.