We conducted a randomized, double-blind study to examine the effects of intravenous (i.v.) diltiazem (0.1 or 0.2 mg/kg) on hemodynamic changes during tracheal extubation and emergence from anesthesia in 80 ASA physical status I patients undergoing elective gynecologic surgery. The effect of diltiazem was compared with that of lidocaine or saline. Anesthesia was maintained with 0.5%-1.5% isoflurane and 60% nitrous oxide (N2O) in oxygen. Muscle relaxation was achieved with vecuronium. The patients were randomly assigned to one of four groups (n = 20 for each group): saline (as a control), 0.1 mg/kg diltiazem, 0.2 mg/kg diltiazem, and 1 mg/kg lidocaine. These medications were given 2 min before tracheal extubation. Changes in heart rate (HR) and blood pressure (BP) were measured during and after tracheal extubation. The HR, systolic BP, and diastolic BP increased significantly during tracheal extubation in the control group (P < 0.05). Diltiazem, 0.1 and 0.2 mg/kg, and lidocaine attenuated the increases in these variables. The inhibitory effect on these cardiovascular responses was greatest with diltiazem 0.2 mg/kg, while the extent of attenuation by diltiazem 0.1 mg/kg was similar to that by lidocaine. We concluded that a bolus dose of i.v. diltiazem 0.1 or 0.2 mg/kg given 2 min before extubation was of value in attenuating the cardiovascular changes occurring in association with tracheal extubation and emergence from anesthesia. This alleviative effect of diltiazem was equal or superior to that of i.v. lidocaine 1 mg/kg.