Introduction: Obstetric anaesthesia and analgesia are associated with many unique and different problems for the anaesthesiologists.Arterial hypotension in pregnant women following spinal anaesthesia continue to be a matter of concern to the anaesthetist. Objective: The study was carried out to compare the efficacy ofIVbolusPhenylephrine, Ephedrine and Mephentermine for maintenance of arterial pressure during spinal anaesthesia in caesarean section. To monitor and record side effects, if any. Subjects and methods: The present study was undertaken on 90 subjects with American society of anaesthesiologist (ASA) type I and II who underwent lower segment caesarean sections under spinal anaesthesia and developedhypotension were selected. Cases were drawn from obstetrics and gynaecology department of NSCB Medicalcollege and Hospital, in whom the decision was taken to perform caesarean section.The subjects are divided into 3 groups of 30 each to receive Group I -Phenylephrine 100ug, Group II - Ephedrine 6mg and GroupIII-Mephentermine 6mg IV bolus. Results: The ANOVA test was used to compare the group among the study groups.In group I (Phenylephrine) it was observed that the peak effect was seen between 1-2 minutes,in group II (Ephedrine) between 3-5 minutes.and in group III(Mephentermine) it was seen between 5-6 minutes . Conclusion- It was concluded that Phenylephrine,Ephedrine and Mephentermine all could be used for maintenance of arterial pressure during spinal anaesthesia for caesarean section.Phenylephrine had an immediate peak,so it may be beneficial for initial control of hypotension. It also shows some advantage over others with regard to reduction in heart rate.