Objective To study the variation of endothelin 1(ET 1) and calcitonin generelated peptide(cGRP) and its clinical implication, and to analyze the influence of ET 1 and cGRP on cerebral arteries hemodynamics in neonates with hypoxic ischemic encephalopathy(HIE). Methods The variation of ET 1,cGRP in cord blood and peripheral blood were prospectively observed at the time of 1 day,3 days and 7 days after birth in HIE and healthy control infants by radioimmuneassay. The cerebral arteries hemodynamics were determined immediately using color Doppler ultrasonography at 1 day after blood samples were obtained. Results (1) The following factors in cord blood and vein one day after birth in neonatal HIE and healthy controls was: ET 1(70?25)ng/L vs (38?19) ng/L ( P