Abstract: Ten isoprenylated flavonoids were isolated from 95% ethanol extraction of Artocarpus heterophyllus, with a combination of various chromatographic approaches, including ODS, MCI, CHP-20 P, Sephadex LH-20 and high performance liquid chromatography. On the basis of physic-chemical characters and spectroscopic data analysis, these compounds were identified as artoheteroid E (1), cycloheterophyllin (2), artelastoxanthone (3), artoindonesianin Q (4), cudraflavone C (5), 8-(γ,γ-dimethylallyl)-5,2',4'-trihydroxy-7-methoxyflavone (6), kuwanon T (7), 6-(3-methylbut-2-enyl) apigenin (8), 5,7,2',4'-tetrahydroxy-6-(3-methylbut-3-enyl) flavone (9), albanin A (10). Among them, compound 1 is a new one, while compounds 2-4 were isolated for the first time from the plant of Artocarpus heterophyllus. All isolated compounds were screened for their inhibitory abilities against cathepsin K. Of them, compounds 3-5, 7 and 10 showed inhibitory effects with the IC₅₀ values of 0.9, 1.6, 4.5, 24.5 and 63.5 μmol·L^-1, respectively.