Socotra Island (Yemen) is one of the best environments where many medicinal plants grow. Dracaena cinnabari (DC) grows there & widely used in folk medicine. This work aimed to analyze the plant chemically & to study the biological effects of some of its purified compounds & aqueous extract (AE) on rat isolated smooth muscles (ISM), perfused heart (PH), blood pressure (BP) and diuresis. Chemical analysis of the resin of DC resulted in the isolation of 5 flavonoids: 4,4-dihydroxy-2-methoxychalcone, 4,4-dihydroxy-2-methoxydihydrochalcone, 7-hydroxy-3-(3-hydroxy-4-methoxybenzyl) chroman,...