BACKGROUND: Pressure damage to respiratory mucosa from overinflation of bronchial cuffs has been implicated as a cause of bronchial rupture, a rare but devastating complication of double-lumen endobronchial tubes. We evaluated the severity of bronchial mucosal damage by bronchial cuff pressure in Robertshaw double-lumen endobronchial tubes. METHODS: Eighteen patients were divided into two groups: in group 1(n=9), bronchial cuff pressure was maintained by 25 mmHg; in group 2(n=9), bronchial cuff pressure was maintained by 35 mmHg during one-lung ventilation. We evaluated the bronchial mucosa by using fiberoptic bronchoscopy before bronchial intubation and following extubation. According to the number of petechia and mucosal hemorrage or tearing, damage scoring was performed. RESULTS: Damage scores of Group 1 are represented by 0(normal mucosa) in number of 3 patients, 1 (small number of petechia) in 2 patients, 2 (large number of petechia) in 3 patients, 3 (mucosal hemorrhage) in 1 patient and above score 4 (mucosal tearing) was not existed. Scores of Group 2 are represented by 0 in number of 1 patient, 1 in 3 patients, 2 in 4 patients, 3 in 1 patient and above score 4 was not existed. CONCLUSION: Degree of bronchial mucosal damage was not related with the bronchial cuff pressure of double lumen tubes.