This study aims to observe the effects of ibutilide on canine cardiac pacing threshold and on induction rates of atrial fibrillation. Eighteen mongrel dogs were anesthetized and administrated with ibutilide. The pacing thresholds and induction rates of atrial fibrillation were measured with and without ibutilide (10-min infusion dose was 0.10 mg kg(-1), followed by a maintaining dose of 0.01 mg min(-1) 30 min later). This study found that ibutilide increases pacing thresholds in dogs. Moreover, there were significant differences between pacing thresholds with and without ibutilide (P < 0.05). Further, ibutilide significantly reduces the induction rates of atrial fibrillation (P < 0.05). Our findings indicate that pacing voltage changes should be closely monitored in patients taking anti-arrhythmic drugs, who are treated with cardiac stimulation or have undergone pacemaker implantation. We also found that ibutilide is an effective drug in preventing or controlling atrial fibrillation.