Background: Caudal anesthesia/analgesia is simple to perform, reliable and safe. Various adjuvants have been utilized with local anesthetic to prolong duration of post-operative analgesia of caudal block in pediatric patients, but with variable results. Aim and Objective: This study is conducted to evaluate the hemodynamics effects and surgical stress response of caudal magnesium sulfate with bupivacaine in children undergoing lower abdominal surgeries. Methods: The study was approved by the local ethics committee, and a written consent was obtained for each subject, and included 60 children ASA classification I and II, aged 1 year to 6 years scheduled for lower abdominal surgeries randomized into one of two groups. after inhalation induction of general anesthesia, standard caudal block was done the participants were randomized into one of two groups either receive 1ml volume containing 50mg of magnesium sulfate (group Mg) added to 1ml /kg bupivacaine 0.25% or 1ml saline as placebo added to the same dose of bupivacaine in group (C). Postoperative pain assessed by FLACC score (acronym for Face, Legs, Activity, Cry and CONSOL ability) and duration of analgesia, postoperative sedation as well as hemodynamic parameters were compared between the two groups. Results: Group Mg had significantly lower FLACC score than group C in the first six postoperative hours. The sedation score was significantly higher only during the first postoperative hours in group Mg compared to group C. There was no statistically significant difference between groups about hemodynamic parameters at any time during the study period. Conclusion: Caudal magnesium sulfate 50mg enhance caudal block and prolongs duration of analgesia with bupivacaine in pediatric patient undergoing lower abdominal surgeries under general anesthesia with minimum adverse effects.