Early identification of cholinesterase inhibitor (AChEI) - poisoned patients who are at risk of respiratory insufficiency or death is crucial to initiate proper interventions. The present study aimed to compare Glasgow Coma Scale (GCS), acute physiology and chronic health evaluation (APACHE II), rapid acute physiology score (RAPS), rapid emergency medicine score (REMS) and simple clinical score (SCS) in order to predict the need of mechanical ventilation (MV) and the risk of mortality in AChEIs poisoning. A retrospective study was conducted on 118 patients with acute AChEIs poisoning. The patients' data were collected from their hospital records. The studied scoring systems were evaluated on admission. Statistical analysis revealed that the median APACHE II, GCS, REMS, RAPS, and SCS differed significantly between MV patients and non-MV as well as between non-survivors and survivors. RAPS and REMS scores showed the highest discriminatory power in prediction of MV and mortality. No significant differences were detected between the studied scores as predictors of MV and mortality except for SCS which was significantly inferior to RAPS and REMS in prediction of MV. In conclusion, the admission REMS or RAPS seem to have valuable prognostic abilities in AChEIs poisoning for identification of patients who require MV or at increased risk of mortality.