Background/Aims: This study aimed to evaluate the correlation between clinical risk factors of post-extubation dysphagia (PED) and the severity of impaired pharyngeal swallowing function assessed via videofluoroscopic swallowing studies (VFSSs). Methods: This study was a retrospective review of medical records. Of 116 patients who were admitted to the intensive care unit and underwent VFSS, 32 who had non-neurologic disorders and experienced prolonged intubation (for more than 48 hours) were diagnosed with PED. The severity of PED was evaluated by using a functional dysphagia scale (FDS) and a penetration aspiration scale (PAS), on the basis of VFSS. Results: The Simplified Acute Physiology Score 3 and total FDS score were positively correlated (r = 0.40, p = 0.02). Intubation duration was positively correlated with total PAS and FDS scores (r = 0.62, p < 0.001; r = 0.65, p < 0.001, respectively). The amounts of residue in the valleculae (RV) and pyriform sinuses (RP) were associated with intubation duration (r = 0.58, p < 0.001; r = 0.57, p < 0.001, respectively). Multivariate regression analysis revealed that intubation duration was significantly associated with the total FDS score, RV and RP subscales of the FDS, and total PAS score. Conclusions: The severity of impaired swallowing function, particularly the amount of residue in the pharyngeal recesses assessed via VFSS, was strongly associated with both severity of medical illness and intubation duration. Intubation duration could be a prognostic factor for assessing impaired swallowing function on the basis of VFSS.