Hypertension is a major risk factor for the development of cardiovascular disease, and medications aimed at reducing blood pressure levels have been shown to reduce the morbidity and mortality. However, many of these medications produce undesirable side effects. As a result, there is much inter-est in the use of alternative medicine in the treatment of hypertension and in the search for plants with hypoten-sive activity and less adverse side effects, reported that a decoction made from the fruits, leaves, and twigs of Annona muri-cata Linn (Annonaceae) is drunk to treat high blood pressure, and there have been reports that the plant extract has antihypertensive properties .A. muricata is found widely in the West Indies, South and Central America, tropical West Africa, and Asia. In the West Indies, various parts of the plant, including the leaves, bark and roots have been used to treat disease conditions such as diabetes and arthritis. Other reported medicinal uses of A. muricata include its anticancer, antibacterial and antifungal actions, as well as, its antinociceptive and anti-inflammatory effects.Phytochemical screening of the leaves of A. muricata has shown it to consist of alkaloids such as reticuline, coreximine, coclarine and anomurine, annomuricin E, annomuricin C, muricato-cin C, gigantetronenin and muricapentocin with anti-oxidant and antitumor properties, as well as, essential oils such as ?-caryophyllene, ?-cadinene, epi-?-cadinol and ?-cadinol.Although there are reports that the A. muricata plant may have antihypertensive properties, the mechanism of action has not been investigated and remains unknown. e present study therefore sought to investigate the pos-sible mechanisms of action of the hypotensive effect of the aqueous leaf extract of A. muricata in normotensive Sprague-Dawley rats.