BACKGROUND: Hypertension and tachycardia usually accompany laryngoscopy and tracheal intubation. Topical and intravenous lidocaine are used in an attempt to blunt these potentially adverse hemodynamic responses, but these effects of lidocaine are controversial. The purpose of this study is to evaluate whether intratracheal nebulized lidocaine and/or intravenous lidocaine attenuate circulatory stimulating response to tracheal intubation. METHODS: Sixty patients, ASA physical status I, scheduled elective surgery, were randomly assigned to receive a preintubation dose of either 5 mL of normal saline intravenously, 4 mL of 4% lidocaine by intratracheal nebulizer, 1.5 mg/kg of 2% lidocaine intravenously, or 4 mL of 4% lidocaine intratracheal nebulizer and 2% lidocaine of 1.5 mg/kg intravenouly. Induction of anesthesia was accomplished with 5 mg/kg of thiopental IV, and 1 mg/kg of succinylcholine was given. Laryngoscopy and intubation was performed, and anesthesia maintained with 2% enflurane in 50% nitrous oxide in oxygen. Blood pressure and heart rate were recorded at preinduction, after induction, and every minute until 5 min after intubation. RESULTS: Intratracheal nebulized lidocaine and/or intravenous lidocaine were effective in attenuating increases in systolic pressure with no detectable difference between them, and failed to attenuate increases in diastolic pressure and heart rate. And significant decrease in systolic pressure 3 min after intubation was detected in intratracheal and intravenous lidocaine group. CONCLUSIONS: These data suggest that intratracheal nebulized lidocaine or intravenous lidocaine is effective in attenuating increase in systolic pressure to tracheal intubation, but intratracheal and intravenous lidocaine has not synergistic effect.