We investigated the effects of 2,3-dibenzylbutane-1,4-diol (DBB), a mammalian lignan derived from human urine, on the contractile response and the 45Ca2+ uptake in the vascular smooth muscle of rabbit aorta. In resting state, DBB did not influence the tension and the 45Ca2+ uptake. DBB inhibited the high KCl- and the CaCl2-induced contraction in the partially depolarized muscle strip. DBB inhibited the noradrenaline- and the angiotensin II-induced contraction, but not the transient contraction evoked by noradrenaline in Ca2+-free solution. DBB completely inhibited the 45Ca2+ uptake induced by high KCl or noradrenaline. These results indicate that DBB inhibits the Ca2+ influx but not the Ca2+ release from the Ca2+ stores.