The effects of hypertonic saline solution (HS) on prostacyclin (PGI2) and endothelin (ET) were evaluated.30 patients under epidural anesthesia during elective operations were infused with 7.5% HS (n=20) or 5% dextrose (n=10) 4ml/kg before anesthesia.PGI2, ET and hemodynamic indices were measured before and 10, 60 min after infusion.In HS group, the PGI2 increased about 51.4%, ET decreased 49.6% and the aortic compliance increased 37.5%. However.after dextrose infusion, PGI2 increased about 23.7% at 60 min, ET increased but dispersedly, with increased TPR and decreased CO, SV.Systolic pressure were declined over 20% in four out of ten patients.It demonstrated that HS could stimulate the secretion of PGI2 and depress ET. These hormonal changes revealed an important role in the course of decreasing TPR, with improving hemodynamios.