Objectives: To determine the vasodilator and anti-vasoconstrictor effect of Olea europaea (olive) leaf hydroalcoholic extract on rataortic rings and the mechanism involved. Design: Experimental. Location: Research and Scientific Development Center, Faculty ofMedicine, Universidad Nacional de San Agustin, Arequipa, Peru. Biological material: Leaves of Olea europaea and aortic rings ofRattus norvegicus, swiss albina variety. Interventions: Hydroalcoholic extract was obtained from Olea europaea leaves. Rat aortic ringswere placed in isolated organ chambers and the vasomotor activity was recorded with isometric tension transducer. Maximum basalcontraction occurred at CaCl2, and 6 mM vasodilator effect was determined at 25, 50, and 100 mg/mL doses of the hydroalcoholicextract. 1H-[1,2,4] oxadiazole [4,3-alquinoxalin-1-one] (ODQ) and nifedipine were used to determine the mechanism of action. W...