Background: Hypotension is a common complication of spinal anaesthesia during caesarean sections, which can pose significant risks to maternal and fetal health. Mephentermine and Phenylephrine are two vasopressors commonly used to manage this condition, but there has been ongoing debate regarding their comparative effectiveness and safety. Objective: This study aimed to compare the effectiveness and safety of Mephentermine and Phenylephrine in treating hypotension following spinal anaesthesia in patients underwent caesarean sections. Methods: In a prospective, randomized, double-blinded, controlled trial conducted at a medical institution, 200 pregnant women undergoing caesarean sections under spinal anaesthesia were randomized to receive either Mephentermine or Phenylephrine. The primary outcome measured was the incidence of maternal hypotension, with secondary outcomes including the required vasopressor dose, the occurrence of adverse events, and neonatal outcomes. The data were analyzed using chi-square tests, independent t-tests, or Mann-Whitney U tests, depending on the nature of the data. Results: The study found no significant difference in the incidence of maternal hypotension between the two groups. However, the Mephentermine group required a significantly higher dose of vasopressor compared to the Phenylephrine group. There were no significant differences in the incidence of adverse events or neonatal outcomes between the two treatment groups. Conclusion: Both Mephentermine and Phenylephrine were effective in managing hypotension during caesarean sections under spinal anaesthesia. Despite the higher doses required for Mephentermine, both drugs had similar safety profiles. These results can guide clinicians in selecting the most appropriate vasopressor for managing spinal anaesthesia-induced hypotension during caesarean sections.