Severe hemodynamic instability is observed during portal vein de-clamping in the form of post-reperfusion syndrome in liver transplantation. The protective effect of magnesium on inflammation and ischemia-reperfusion injuries of various organs is evident, but its role in the prevention of post-reperfusion syndrome in liver transplantation is not clear. We investigated the effect of magnesium sulphate on the incidence of post-reperfusion syndrome during living donor liver transplantation. The secondary outcomes were the requirement of vasopressor boluses and levels of serum magnesium, lactate and serum C-reactive protein. Seventy living donor liver transplant recipients were randomized into a magnesium (M) group (n=35) or normal saline (N) group (n=35). The patients in group M received 35mg/kg of magnesium sulphate, 30 minutes after the beginning of the anhepatic phase, and patients in group N received normal saline. The incidence of post-reperfusion syndrome in group M and group N was 34.29% and 40%, respectively, with no significant difference. The requirement for rescue vasopressor boluses and levels of C-reactive protein and lactate were also comparable between the two groups. However, the incidence of hypomagnesemia at the end of surgery was significantly higher in group N (37.1% vs. 14.28%, p=0.027). Magnesium does not appear to prevent post-reperfusion syndrome. However, hypomagnesemia is more frequently seen during liver transplantation. Hence, serum magnesium should be routinely monitored and administered during liver transplantation.