In long-term mechanically ventilated patients, dysphagia is a common and potentially life-threatening complication, which can lead to aspiration and pneumonia. Nevertheless, many intensive care unit (ICU) patients are fed by mouth without evaluation of their deglutition capability. The goal of this work was to evaluate the prevalence of aspiration due to swallowing disorders in long-term ventilated patients who were fed orally in the ICU while having a blocked tracheotomy tube. In all, 43 patients participated-each underwent a fiberoptic investigation of deglutition on the day of admission to the rehabilitation clinic. A total of 65 % of the patients aspirated, 71 % of these silently. There were no associations between aspiration and any of the following: gender, indication for mechanical ventilation (underlying disease) or the duration of intubation and ventilation by tracheotomy tube. However, the association between aspiration and age was statistically significant (p = 0.041). Aspirating patients were older (arithmetic mean = 70 years, median = 74 years) than patients who did not aspirate (arithmetic mean = 66 years, median = 67 years). Intubation and add-on tracheotomies can lead to potentially life-threatening swallowing disorders that cause aspiration, independent of the underlying disease. Before feeding long-term mechanically ventilated patients by mouth, their ability to swallow needs to be investigated using fiberoptic endoscopic evaluation of swallowing (FEES) or a saliva dye test, if a cuff deflation and the use of a speaking valve are possible during spontaneous respiration.