OBJECTIVE To examine the effects of landiolol on the QT interval, rate-corrected QT (QTc) interval, QT dispersion (QTD), and rate-corrected QTD (QTcD) during tracheal intubation using computerized measurement. METHODS Randomized, double-blinded study. METHODS Dokkyo Medical University Hospital operating room. METHODS 30 ASA physical status I patients scheduled for elective surgery. Patients were randomized to receive either normal saline (saline group) or landiolol (landiolol group; one-min loading infusion of 0.125 mg/kg followed by 0.04 mg/kg/min infusion). Immediately after the start of administration of saline or landiolol, anesthesia was induced with intravenous (IV) fentanyl two microg/kg, propofol 1.5 mg/kg, and vecuronium 0.1 mg/kg. Six minutes after administration of saline or landiolol, tracheal intubation was performed within 20 seconds. METHODS Mean arterial pressure (MAP), RR interval, QT interval, QTc interval, QTD, and QTcD were consecutively recorded during the induction. RESULTS There was no significant difference in MAP between groups during the study. RR interval in the landiolol group was significantly longer than in the saline group from two minutes after the start of the landiolol infusion to the end of the study. The QT interval in the landiolol group was significantly shorter than in the saline group from start of the infusion to 4 minutes after tracheal intubation. The QTc interval, QTD, and QTcD in the landiolol group were significantly shorter than those in the saline group from immediately after tracheal intubation to the end of study. CONCLUSIONS A bolus of landiolol 0.125 mg/kg followed by an infusion of landiolol 0.04 mg/kg/min may reduce the risk of cardiac arrhythmias during induction of anesthesia.