Transient Complete left bundle branch block (CLBBB) is defined as an intraventricular conduction defect that subsequently returns, if only temporarily, to normal conduction. CLBBB is usually permanent and associated with a structurally abnormal heart, especially the heart with artherosclerotic, hypertensive, or valvular disease. However, CLBBB may appear transiently and intermittently during anesthesia, although it is uncommon.It may be related to the changes in heart rate or blood pressure without any heart disease. Also, transient CLBBB may develop during anesthesia in the absence of associated tachycardia or hypertension. We report a case of transient CLBBB which developed without apparent associated hypertension or tachycardia during general endotracheal anesthesia.