Abstract: MHDF is a synthetic isoflavone derivative with anti-ischemic effect. In this paper, the effects of MHDF on in vivo hemodynamics and in vitrocontraction of rat aorta were reported. MHDF (3～12.8mg/kg ) was found to decrease±dP/dt_max, V_max, V_pm and LVSP, prolong T-dP/dt_max of left ventricle and slow, the HR in rats. It was also shown to inhibit thechanges of heart, performance induced by CaCl₂ in rats. In isolated rat aorta, M HDF caused a noncompetitive antagonism of nor, adrenaline-and CaCl₂-induced contraction with the pD₂' of 3.11±0.21 and 3.73±0.07. The high K⁺-evoked contraction with IC₅₀ of 17.6 μmol/L was also found to be inhibited. The results suggest that the effect of MHDF on vascular muscle is different from that of an α-blocker and may be attributable to inhibition of extracellular calcium influx or intracellular calcium release.