Although the endotracheal tube (ETT) cuff may be associated with tracheal morbidity, cuffed tubes may reduce the aspiration risk in oral procedures. Dentists must use a mouth prop to facilitate oral visualization and to protect the oral soft tissues during dental rehabilitation under general anaesthesia (DRGA). The aim of this study was to evaluate the effect of mouth prop on endotracheal tube intracuff pressure in children during DRGA. Two-hundred and three ASA I-II patients, < 18 years of age (mean: 5.3 +/- 2.4 years) were included in the prospective observational study whose comprehensive dental treatment was performed under general anaesthesia. Following the induction of general anaesthesia, placement of a cuffed endotracheal tube which was an appropriate size for children was fixed. The intracuff pressure was measured intermittently after the intubation (baseline) (T0), immediately after the mouth prop (T1), 30 min after the mouth prop (T2), after taking out the mouth prop (T3) and just before extubation (T4). The mean intracuff pressure was 28.3 +/- 2.01 cm H2O at T0. The mean intracuff pressure significantly increased at T1 (30.8 +/- 2.7) and T2 (29.6 +/- 3.7) compared to T0 (P < 0.001). No significant differences were observed between the duration of the procedure and intracuff pressure or postoperative complications (P > 0.05). Cough, sore throat and nausea were observed in 4, 1 and 5 patients, respectively. Because a mouth prop may increase the intracuff pressure of ETT, strict measurement and readjustment of cuff pressures should be employed when used in children during DRGA.