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Background & Objective: The cuff of the endotracheal tube is securing for mechanical ventilation during anesthesia. Diffusion of N2O in the cuff results in an increase in cuff pressure. The different method was used for the control of cuff pressure, but may have difficulty and side effect. This study was to determine whether inflating the ETT cuff with air, Lidocaine 1% or N2O with O2, prevent the increase in cuff pressure during N2O anesthesia. Materials & Methods: In this randomized control trial study after obtating ethics committee 224 patients went understudy, these patients divided in 2 blocks (Sufe, Roach) and the one of the each block were randomized into 3 groups. Group, air Lidocaine 1% N2O with O2 difficult intubation and the film anesthesia with less than 30-min were excluded. All patients were similarly anesthetized and performed tracheal intubation. The pilot balloon of the endotracheal tube cuff was connected to a Japanes pressure manometer. The first pressure was measured immediately and further reading at 10-minute intervals for 70 minutes. The results were readings analyzed using T-test, paired T-test, ANOVA and the Chi-square test. A P-value of <0.05 was considered significant. Results: Cuff pressure increased gradually during anesthesia in-group air but remained stable in group’s Lidocaine and N2O with O2. The cuff pressure had significant differences between the Supa and Roach groups in all of the times during anesthesia (P<0.05). Conclusion: Inflating the ETT cuff with Lidocaine 1% or N2O/Oxygen mixtures are methods of keeping intracuff pressure stable during N2O anesthesia due to N2O diffusion the cuff tube causes increase the cuff pressure. We suggest that continuous monitoring of the UCP during anesthesia to be carried out.