Postoperative sore throat is the common complaint of patients after endotracheal intubation. Hypothesis and recent studies, usually with high concentration of local anesthetics, suggested that continuous application of local anesthesia at the contact area between the endotracheal tube cuff and trachea would reduce both the incidence and severity of postoperative sore throat by blocking the tracheal pain receptors with local anesthetic delivered via endotracheal tube (ETT) cuff. The objective of the study was to investigate the effectiveness of using conventional available 2% lidocaine filling in endotracheal cuff on reduction of the incidence and severity of postoperative sore throt One hundred and fifty patients, ASA physical status I and II, were randomly allocated into 3 groups where their ETT cuffs were filled with 2% lidocaine, saline or air in volume just sufficient to prevent retrograde leakage around the cuff while ventilating with the tidal volume of 10 ml./kg. Variables typically associated with postoperative sore throat, including endotracheal cuff design, endotracheal tube size, intubation technique, laryngoscope blade, airway placement, suctioning technique, and anesthetic technique were all controlled. Volume of the agents filled at intubation and extubation and cuff pressure measured at intubation and prior to extubation were all recorded. VAS (visual analog scale) and severity of sore throat at one hour and 24 houre following extubation, was used to assess the presence and severity of postoperative sore throat. Two patients in each study group (total 6 patients) were excluded due to failure to meet extubation criteria at the end of operations. Incidence of sore throat among 2% lidocaine group,saline group and air group were 3/48, 8/48 and 7/48 respectively. There was no statistical significant in both incidence and severity among groups. The volume and pressure in air group prior to extubation differed significantly from 2% lidocaine and saline groups. In conclusion, we failed to demonstrate the difference in postoperative sore throat among the 3 groups, 2% lidocaine, saline and air. Larger sample size is needed to elucidate the effectiveness of 2% lidocaine in reducing incidence and severity of postoperative sore throat due to lower incidence of postoperative sore throat in the population study.