Background. In this study we aimed to analyze the effect of perioperative magnesium sulphate (MgSO4) on minimal alveolar concentration (MAC) of desflurane using bispectral index (BIS) monitoring. Patients and methods. Sixty patients undergoing abdominal surgery under general anesthesia were randomized into two groups: Mg - receiving perioperative MgSO4 supplementation and C - control. Anesthesia was titrated to maintain the BIS value between 45-55. Results. MAC values, tachycardia and hypertension during intubation was found to be lower in group Mg compared to group C (p<0.001). Time to extubation, verbal cooperation and eye opening was longer in patients receiving infusion of MgSO4 (p<0.001). Conclusion. We concluded that perioperative MgSO4 infusion may be used as an adjunct as it decreases MAC of desflurane and suppresses the hemodynamic response to intubation.