A new oxepinochromenone, rugosachromenone A (1), seven new flavonoids, rugosaflavonoids A-G (2-8), and 11 known compounds (9-19) were isolated from the flower buds of Rosa rugosa. Compound 1 is found from Nature for the first time. Compound 2 displayed cytotoxicity against NB4, SHSY5Y, and MCF7 cells with IC50 values of 2.2, 2.5, and 2.3 μM, respectively, and 3 was toxic to A549 and MCF7 cells with IC50 values of 1.2 and 2.8 μM, respectively.