BACKGROUND: Lidocaine sprayed down the endotracheal tube (ETT) before extubation and during ETT removal was reported to prevent increases in blood pressure and heart rate during and after extubation. We hypothesized that lidocaine administered via this route would suppress the cough reflex associated with tracheal extubation. METHODS: Eighty-five patients requiring intubation in the supine position were studied. All patients received a standardized anesthetic protocol. At the end of surgery, the patients were randomly divided into three groups and given no drug (group 1-control), given 1 mg/kg 2% lidocaine sprayed down the ETT 5 minutes prior to extubation (group 2), or given intravenous lidocaine (IVL) 1 mg/kg 3 minutes prior to extubation (group 3). Extubation was performed when the patients met the criteria of extubation. Number of coughs was recorded from 5 minutes before until 5 minutes after extubation. Each value was compared among the three groups. RESULTS: Seventy-five patients completed this study (n = 25 for each group). The incidence of patients experiencing coughing was decreased in group 2 (P = 0.03), compared with group 3 or the control. Number of coughs per patient was significantly less in group 2 (P = 0.00). IVL did not significantly diminish the incidence or the amount of coughing compared with the control. CONCLUSIONS: Lidocaine sprayed down the ETT suppresses cough reflex and is more effective than IVL in blunting the cough reflex. This study indicates that lidocaine sprayed down the ETT has a topical anesthetic effect suppressing the cough reflex.