Objective: The objective of this study was to compare the hemodynamic effects of use of prophylactic intravenous ephedrine with ephedrine use on as needed basis in patients receiving spinal anesthesia for caesarean sections. Study design: A double blind, randomized, comparative trial Setting: Department of Anaesthesiology, Critical Care, and Pain Magement, Shifa International Hospital Duration: October 2007 to March 2008 Methodology: Seventy patients were recruited who were scheduled to receive spit anaesthesia for C-section. The patients were randomized into two groups (A and B). In patients of Group A (control group) ephedrine was used to treat h ypotension when indicated, while in Group B (inter vention group), patients received prophylactic ephedrine soon after the subarachnoid block. Hemodvnamic changes were recorded and the data was analysed. Results: In Group A, the blood pressure dropped in a higher number of patients [23 (65.7%)], as compared to Group B [6(17.1%)]. This difference was statistically significant (p<0.001). Conclusion: Prophylactic ephedrine is better than ephedrine prn in prevention of hypotension in patients receiving spinal analgesia for C-Section.