Abstract: Objective: To observe the effect of polygeline in preventing hypotension and other side effects during combined epidural and spinal anesthesia(CESA) in cesarean section.Methods: Forty cases of ASA grade Ⅰ-Ⅱ receiving selective cesarean section under CESA were randomly divided into two groups(n=20).At the beginning of the anesthesia,each group were infused 500 ml polygeline and lactated ringer solution.The changes of systolic blood pressure(SBP) and heart rate(HR) before and after anesthesia,the side effects such as the incidence of hypotension,nausea and vomiting,and the number of cases using ephedrine were observed.Results: The SBP decreased significantly in L group compared with F group(P<0.05-P<0.001).The incidence of hypotension,nausea,vomiting and the cases using ephedring were significantly higher in L group than that in F group(P<0.05),but there was no significant difference in HR (P>0.05).Conclusions: Preloading infusion during combined epidural and spinal anesthesia may effectively prevent hypotension and other side effects in cesarean section.