<jats:title>Abstract</jats:title><jats:p>Himbacine is a plant alkaloid isolated from <jats:italic>Galbulimima baccata</jats:italic>. Intravenous administration of himbacine produced a fall in blood pressure and heart rate in anesthetized normotensive cats. These effects were similar in areflexic and normal cats, suggesting direct peripheral action with no central component involvement. Presence of himbacine did not alter the preganglionic stimulation of cat nictitating membrane, ruling out the possibility of ganglion blockade. In isolated rabbit aorta, himbacine inhibited K<jats:sup>+</jats:sup>‐induced contraction, an effect similar to that of papaverine. These data indicate that antihypertensive and bradycardiac actions of himbacine are mediated through its direct depressant action on myocardium and blood vessels, and that the compound is relatively safe with i.p. LD<jats:sub>50</jats:sub> in mice of 230 mg/kg.