We studied the effect of intravenous injection of verapamil (0.05 mg/kg or 0.1 mg/kg) on cardiovascular changes during tracheal extubation and emergence from anesthesia and compared the efficacy of the drug with that of diltiazem (0.2 mg/kg). Eighty patients (ASA physical status I) who were to undergo elective gynecological surgery were randomly assigned to one of four groups (n = 20 each): saline (control), 0.05 mg/kg and 0.1 mg/kg verapamil, and 0.2 mg/kg diltiazem. These medications were given 2 min before tracheal extubation. Anesthesia was maintained with 0.5%-1.8% isoflurane and 60% nitrous oxide in oxygen. Muscle relaxation was achieved with vecuronium. Changes in heart rate (HR) and arterial blood pressure (AP) were measured during and after tracheal extubation. In the control group, the HR and systolic and diastolic AP increased significantly during tracheal extubation. Both calcium channel blockers attenuated the increases in these variables. The inhibitory effect was greatest with verapamil 0.1 mg/kg, while the alleviative effect of verapamil 0.05 mg/kg was inferior to that of diltiazem 0.2 mg/kg. These findings suggest that a bolus injection of verapamil 0.1 mg/kg given 2 min before tracheal extubation is a more effective prophylactic for attenuating the cardiovascular changes associated with extubation than is diltiazem 0.2 mg/kg.