In our hospital, twenty-one cases of endotracheal tube cuff rupture during naso-tracheal intubation were noted in cases using 725 polyvinyl chloride (PVC) tracheal tubes. We analysed the causes of cuff troubles in these 21 samples of tubes. When the cuffs were inflated, they were not capable of containing the air in most cases. Some cuffs had small holes (described as pinholes), and the others had longer slits on scrape marks and burst. These scrape marks may have been caused by the object with sharp edges such as spina or crista of the nasal septum, or otherwise by the tip of intubation forceps. The cuff material appeared to be slightly hardened in some samples which may be due to the lubrication. We usually lubricated the tube with lidocaine spray or gel formulation and then sometimes placed it in hot water to soften it for avoiding naso-mucosal injury. It is not generally recommended to place tubes in hot water, as this procedure may soften the cuff and make it more suspectible to damage. The clarification is also needed on the use of lidocaine. Although the gel formulation is acceptable, but the spray formulation is known to react with cuff material and make it more susceptible to inducing blistering, pinholes and sudden rupture of PVC cuffs. We conclude that these cuff damages might have occurred from various causes. A main cause must be passing the tube through the narrow nasal turbinate with spina or crista. Other causes could not only be the use of Magill forceps but also lubrication of the tube with lidocaine spray and placing it in hot water.