en Descriptive & Survey <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="background:white"><span cambria="" style="font-family:">Aims:</span></span></b><span style="background:white"><span cambria="" style="font-family:"> Due to the adverse effects of injectable opioids after surgery and the suggestions of many researchers to find a reliable way to replace opioid use and also the contradictory results of the most appropriate method of using magnesium sulfate to control and reduce postoperative pain, this study was to evaluate the effect of intravenous infusion of magnesium sulfate on opioid use on reduce pain after laparotomy in patients with a history of radiotherapy.</span></span><span style="background:white"><span style="font-family:"Cambria",serif"></span></span></span></span></span><br> <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="background:white"><span cambria="" style="font-family:">Instrument & Methods:</span></span></b><span style="background:white"><span cambria="" style="font-family:"> In this descriptive cross-sectional study, 50mg/kg of bolus magnesium sulfate was injected before surgery; then, after the end of surgery, 500mg/hr of the same drug was injected. Pain intensity was assessed in patients in two different groups.</span></span><span style="background:white"><span style="font-family:"Cambria",serif"></span></span></span></span></span><br> <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="background:white"><span cambria="" style="font-family:">Findings:</span></span></b><span style="background:white"><span cambria="" style="font-family:"> No statistically significant relationship was observed in the hemodynamic status of patients in both groups before, during and after surgery. The rate of drug use in the intervention group was associated with a decrease over time, while no significant reduction was seen in the control group. Also, no statistically significant relationship was observed between the two groups after surgery.</span></span><span style="background:white"><span style="font-family:"Cambria",serif"></span></span></span></span></span><br> <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="background:white"><span cambria="" style="font-family:">Conclusion:</span></span></b><span style="background:white"><span cambria="" style="font-family:"> Using magnesium sulfate, although it is effective in reducing the need for opioids in laparotomy patients with a history of radiotherapy, but can not reduce the need for opioids to zero.</span></span></span></span></span> Laparotomy, Radiotherapy, Pain, Magnesium Sulfate 67 70 http://gmedicine.de/browse.php?a_code=A-10-1-11&slc_lang=en&sid=2 A. Nasseri 10031947532846001391 10031947532846001391 Yes Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran F. Mahdavi 10031947532846001392 10031947532846001392 No Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran