Background: Although various anesthetic techniques can be used in different kinds of surgeries, spinal anesthesia has received considerable attention for the lower abdomen and lower extremities surgeries and cesarean section. This study aimed at comparing the effect of adding epinephrine 1:1000 and 1:10000 to lidocaine and fentanyl in spinal anesthesia on the prolongation of paralysis, analgesia and hemodynamic changes in pregnant women candidate for cesarean section.Methods: A double blind randomized clinical trial was carried out on 66 pregnant women (equally sized control and treatment groups of 33) in 2011. After randomizing the participants into two groups of recipients of epinephrine 1:1000 plus lidocaine 5% and fentanyl (control group) and recipients of epinephrine 1:10000 with lidocaine 5% and fentanyl, (treatment group), the participants' systolic and diastolic blood pressure and heart rate were recorded before and 1, 3, 5, 10, 15 minutes after procedure. Besides the prolongation of paralysis and analgesia, the presence of postoperative nausea and vomiting were evaluated. The outcome of the study was analyzed using SPSS software and via t test, x2 test and RMANOVA.Results: The mean age (standard deviation) of the participants was 29.3(4.4) and 28.2 (4.5) in the treatment and control groups, respectively. There were no statistical significance between the participants' prolongation of paralysis, analgesia, the frequency of nausea and vomiting, and the average values of hemodynamic variables between the two groups.Conclusion: The use of epinephrine 1:10000 along with lidocaine and fentanyl is recommended in spinal anesthesia in pregnant women candidate for cesarean section.