All patients in both groups were assessed and monitored for the intravenous remifentanil consumption, quality of pain relief using a six point pain intensity scale in the responsive but still intubated patient and visual analogue score after tracheal extubation. Level of consciousness and ventilatory frequency were also assessed. Arterial blood gases, serum magnesium concentrations, serum cortisol and blood glucose levels were also monitored. Side-effects related to magnesium overdosage postoperative nausea and vomiting were recorded during the study period.The results of the statistical analysis of the data obtained showed that there is significant decrease in the overall remifentanil consumption in the magnesium group. However, maintenance of low pain scores and ensuring that patients felt comfortable at rest, may have limited the marginal benefit of magnesium, and a more pronounced opioid sparing effect might be found with higher pain scores or with a larger dose of magnesium.