Background: Carbon monoxide (CO) poisoning is one of the most common fatal poisoning worldwide. Laboratory parameters and imaging studies have been used to predict late cardiac and neurological complications in CO poisoned patients. However, very few studies have applied scoring systems as predictors of CO poisoning outcome. Objectives: To evaluate various scoring systems used in emergency settings [Rapid Emergency Medicine Score (REMS), Modified Early Warning Score (MEWS) and Simple Clinical Score (SCS)] for outcome prediction in acute CO poisoned patients. Methodology: It was a cross-sectional study that was conducted on forty five acute CO poisoned patients. It was composed of two parts; retrospective (From 1 st of January 2020 to 28 th of February 2021) and prospective part (From 1 st of March 2021 to 30 th of June 2021). Patients with major medical conditions, pregnant females, smokers and those exposed to associated trauma and other substances in addition to CO were excluded. Using patients' data on admission, REMS, MEWS and SCS were calculated and compared for prediction of outcome. Results: On admission REMS, MEWS and SCS showed significant elevation in both mechanically ventilated and non-survivors when compared to nonmechanically ventilated patients and survivors. MEWS was excellent predictor for requirement of mechanical ventilation (AUC > 0.9). For mortality prediction; REMS, MEWS and SCS were all excellent (AUC = 1). Conclusion: REMS, MEWS and SCS are simple, rapid, reliable and applicable scoring system in predicting mechanical ventilation requirement and in-hospital mortality in acute CO poisoning.