Many options are available for post–operative analgesia including systemic analgesics and regional techniques. The aim of this study was to compare analgesic duration of combination of fentanyl and neostigmine with  intrathecal  bupivacaine, fentanyl and neostgmine alone with  intrathecal  bupivacaine.Method: 164 patients of ASA grade I and II, scheduled for elective Total Abdominal Hysterectomy under subarachnoid block were randomly allocated to four groups (n=41): Group A received 15mg bupivacaine  intrathecally.Group B received 15mg bupivacaine plus 25 micrograms of  fentanyl intrathecally.Group C received 15mg bupivacaine plus 25 micrograms neostigmine  intrathecally.Group D received 15mg bupivacaine plus 25 micrograms  neostigmine and 25 micrograms fentanyl intrathecally with total volume made upto 4.0ml with NS in each group.Result: Duration of analgesia in post operative period was group A (126.05±19.33 minutes),group B (208.2±15.74 minutes),group C (194.37±15.54 minutes),group D (290.8±20.24 minutes. Conclusion: The combination of intrathecal neostigmine and fentanyl with bupivacaine significantly prolonged post operative analgesia  as compared to other three study groups.