An Armored tube is known to be the most effective in maintaining of airway patency during anesthesia in any position. Unfortunately, the tube itself may become the cause of airway obstruction. One of the known complications of the armored tube is a separation of the individual latex layers. This can be caused by herniation into the lumen. Diffusion of nitrous oxide into the inner hernia considerably intensifies the obstruction. The bubbles in the tube wall arise during manufacturing as well as during resterilization. A 62-year-old man with herniation of lumbar disc herniation was intubated with a 8.0 mm armored tube for general anesthesia. 30 minutes later, we experienced signs of partial endotracheal tube obstruction including high arterial PCO2 and inspiratory pressure in prone position. Then, tube suction with catheter was done and signs was slightly improved. But, 90 minutes later, passage of suction catheter was impossible. When operation was finished, patient was turned to supine position. We exchanged the tube with another tube and found inner wall herniation into the armored tube lumen caused by layer separation.