Caffeic acid, chlorogenic acid, methyl ester of chlorogenic acid, tricin, apigenin, 4’-O- methyl ether of apigenin (acacetin), quercetin and 3’-O-methyl ether of quercetin were isolated from the flowers of Lonicera japonica Thunb., Caprifoliaceae, grown as a medicinal plant for commercial purposes in Vietnam. Their chemical structures were determined by EIMS, 1 H NMR, 13 C NMR, DEPT, COSY, HMQC and HMBC.