The decision of intubation and mechanical ventilation in poisoned patients with impaired consciousness can be a difficult task. The present study aimed to evaluate the power of Glasgow Coma Scale (GCS), acute physiology and chronic health evaluation (APACHE II), rapid acute physiology score (RAPS) and rapid emergency medicine score (REMS) at admission in predicting the need of intubation and mechanical ventilation in drug overdose patients with disturbed consciousness level (DCL). This prospective observational study was conducted on 104 poisoned patients who were admitted to Tanta Toxicological Unit with a DCL. Four scoring systems (GCS, APACHE II, RAPS and REMS) were recorded for all patients on admission. Discrimination was evaluated using receiver operating characteristics curve and calculating the area under the curve (AUC). Twenty-four cases required mechanical ventilation. The mechanically ventilated patients had significantly lower value of GCS and higher values of APACHE II, REMS and RAPS than other group (p < 0.001). Although the APACHE II score has the best AUC value (0.796) in predicting mechanical ventilation, there was no statistically significant difference between the four scores. GCS > 8 had 100% negative predictive value, while REMS > 8 had 100% positive predictive value.