Aim The effects of melittin (a polypeptide from bee venom) on rat aorta and the relation with Ca 2+ influx were studied in this article. Methods The contractile test of the isolated aorta rings and the assay method of 45 ?Ca influx were used. Results In endothelium-intact aorta rings, melittin did not influence the rapid contractions induced by phenylephrine (PHE), but could inhibit the continuing contractions in the concentration dependent manner. In endothelium-denuded aorta rings,melittin did not have the effect on the contractile responses induced by PHE. Melittin did not cause the contraction in endothelium-intact aorta rings, but induced significantly contractions and increased the 45 ?Ca influx in endothelium-denuded aorta rings, these effects were partially antagonised by cartopril and bepridil respectively. Conclusions Melittin could cause the endothelium dependent relaxations to vascular smooth muscle, and the releasing renin and Na + - Ca 2+ exchange system could play partial role in the contractions of the endothelium-denuded vascular.