Background: Abdominal hysterectomies are exceedingly common procedure with an increased incidence of acute and chronic pain. The use of intrathecal additives prolongs the block duration, decrease post-operative pain& opioid consumption with better recovery than general anesthesia. Objectives: This study aims to compare the analgesic efficacy and safety of adding ketamine, dexmedetomedine & magnesium sulphate to bupivacaine intrathecally in lower abdominal hysterectomies. Methods: This study is registered after approval by the ethics committee Benha University, Egypt. 100 patients aged 18 – 50 years scheduled for lower abdominal hysterectomy were enrolled and randomly assigned into 4 groups (25patients each): group I patients were given 15mg bupivacaine plus 0.5ml distilled water only intrathecally group II were given , mixture of Bupivacaine 15mg + 0.1mg/kg ketamine only intrathecally. Group III were given, mixture of Bupivacaine 15mg + 10 ug dexmedetomidine intrathecally. Group IV patients were given mixture of Bupivacaine 15mg + 50 mg magnesium sulfate intrathecally. Patients were followed up for 24 hours postoperatively for vital signs, VAS score, first request of rescue analgesia and total morphine consumption and side effects. Results: Dexmedetomedine plus bupivacaine intrathecally compared to bupivacaine alone or with ketamine &magnesium sulphate addition prolonged the mean time of first request of analgesia (11±1), (2 ±1), (7±1), (6±1) respectively (P < 0.001), reduced total morphine consumption (6±1), (16±1), (11±1), (13±1) respectively (P 0.05). Conclusion: Bupivacaine- dexmedetomedine, bupivacaine-ketamine& bupivacaine - mgso4 intrathecally produced longer duration of analgesia than bupivacaine alone post-operatively in hysterectomy operations, the bupivacaine-dexmedetomedine mixture had the longest duration of analgesia among the four groups with the least side effects &least VAS so it is more safe & effective to the patients.