Purpose: It is known that aspiration pneumonitis is associated with high mortality and morbidity following overdose. However, until now, few domestic studies on this subject have been conducted. The main aim of this study is to investigate the risk factors associated with aspiration pneumonitis in intubated patients following overdose. Methods: Among 654 adult overdosed patients who visited our institution from Jan. 2006 to June 2008, we enrolled 70 intubated patients within 24 hours after their overdose, and we reviewed the medical records to collect the data. This data was processed by univariate analysis, followed by multiple logistic regression analysis. P values <0.05 were deemed statistically significant. Results: In our study, a high incidence of pneumonitis was seen in the patients with an older age, a lower GCS and a high poisoning severity score or a high comorbidity score (p<0.05). Compared with the non-pneumonitis group, the pneumonitis group had a higher incidence of intubation (6% vs 61.8%, respectively, p<0.05). The main cause of intubation was a decreased mentality (68.6%). Older age, a high comorbidity score, irrigation without airway protection, relative hypoxemia and hyperkalemia were the risk factors of aspiration pneumonitis in the intubated overdosed patients (p<0.05). Among these factors, age, a high potassium level and airway protection might be significant predictors of aspiration penumonitis (p<0.05). Conclusion: Older age, a high potassium level and irrigation without proper airway protection may be the significant factors that can predict aspiration pneumonitis in patients who are intubated within 24 hours after overdose, although the further investigations on this are needed.