In this study, QT prolongation due to ondansetron administration was below the 'important' value according to the recommendations of the ICH. No cases of cardiac arrhythmia were reported in any of the partients. Thus, routine ECG monitoring in patients given ondansetron due to the risk of QTc prolongation does not seem cost-effective when evaluated together with additional factors such as its negative impact on emergency patient flow, waste of personnel and time, and increase in healthcare costs. In the absence of a known risk of cardiac arrhythmia, IV administration of 4 mg and 8 mg of ondansetron doses no risk of QT prolongation in the emergency population.