Tracheoscopic evaluation of the tracheal mucosa change resulting from different inflating pressure values of the endotracheal tube cuff were performed in this study. Eighteen dogs of different breeds, sexes, ages, and sizes were randomly selected and included in the study. After induction, the dogs were intubated and general anesthesia was maintained with inhalation for surgery. The dogs were randomly grouped according to the following cuff pressures: 25 mmHg in group I (GRl) (n = 6), 50 mmHg in group II (GRU) (n = 6) and random cuff pressures in group III (GRUI) (n = 6). At the end of the surgery, before extubation, tracheoscopies were performed in the dogs. Tracheoscopic examinations revealed mucous fluid accumulation, mucoid plaque, mucosal ruffles, mucosal ischemia, tracheal enlargement, vascular congestion, mucosal hemorrhage and mucosal lacerations. Tracheal lesions were more severe in GRU than in GRl. The underlying tracheal pathologic changes were mucosal nodule, mucosal hyperemia, tracheomalacia and tracheal collapse (grade 1). In conclusion, the endotracheal tube cuff pressure can lead to tracheal lesions; therefore, tracheoscopic examination, if possible, can be used in clinical practice to detect underlying tracheal pathologies before intubation, which can be helpful for preventing tracheal lesions.