Six hitherto unknown prenylated 2-phenoxychromones, epimedonin G (1), 7-O-methylepimedonin G (2), and epimedonins H-K (3-6), and two new prenylflavonoids, epimedonin L (7) and 3″-O-desmethylspinorhamnoside (8), were isolated from an ethanol extract of the aerial parts of Epimedium brevicornum. Their structures were established on the basis of spectroscopic data interpretation. Compound 7 exhibited cytotoxic activity when evaluated against four human cancer cell lines (HL-60, A-549, MCF-7, and SW-480), with IC50 values of <10 μM. In addition, the structures of epimedonins A and B (9a, 10a), recently isolated from E. koreanum, were corrected by reanalysis of the published NMR data.