Abstract: In the course of continuing research for finding bioactive compounds from Indonesian plants, the leaves of Artocarpus communis was extracted by ethanol. This extract partitioned with n-hexane-water (1:4) and then water extract was partitioned with dichloromethane. Dichloromethane extract was purified by column chromatography techniques on silica gel to afford yellow crystal (F-1). Based on LC-MS, 1H-NMR and 13C-NMR (1D and 2D) spectra and compared with previous spectral data, it was identified as prenylated flavonoid, 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-yl] 1-propanone. This compound showed significant cytotoxicity against murine P-388 leukemia cells.