BACKGROUND: Hypotension after epidural anesthesia for cesarean section is a serious complication despite several measures used to reduce its incidence. This study evaluates the effect of volume of crystalloid preload in prevention of hypotension and change of hematdegrees Crit during epidural anesthesia. METHODS: Thirty patients who scheduled for elective cesarean section were divided into two groups. The group I(n=15) received 10 ml/kg and group II(n=15) received 20 ml/kg of Ringer's lactate over 20 minutes before epidural anesthesia. Hypotension was defined as a decrease in systolic blood pressure to less than 90 mmHg or to less than 70% of baseline value, and was treated with 5 mg of intravenous ephedrine. Systolic blood pressure and heart rate were measured every one minute during the first 20 minutes after epidural anesthesia. Apgar score and hematdegrees Crit level were measured. RESULTS: There was no significant difference in the incidence of hypotension and used ephedrine dose. There was no significant difference in Apgar score. There was significant fall in hematdegrees Crit after fluid loading and postoperation 1st day in group II than group I. CONCLUSIONS: The above results show that 10 ml/kg of fluid preload is more reasonable than 20 ml/kg to prevent hypotension and maintain less decreased level of hematdegrees Crit.