Five new prenylated flavonoids, artelastoheterol (1), artelasticinol (2), cycloartelastoxanthone (3), artelastoxanthone (4), and cycloartelastoxanthendiol (5), along with five known compounds, were isolated from the root bark of Artocarpus elasticus. The structures of 1-5 were elucidated by spectroscopic methods and through comparison with data reported in the literature. The previously known compound artonol A (6) exhibited cytotoxic activity against the A549 human cancer cell line, with an ED50 value of 1.1 microg/mL.