A 49-year-old man with a left upper lobe mass lesion was admitted for evaluation. An open thoracotomy biopsy confirmed tuberculosis. A left upper lobectomy was then performed under general anesthesia. The operative procedure was remarkable for a 15-second acute episode of cardiac asystole during the aortopulmonary window lymph node dissection. After injection of epinephrine and open cardiac massage, sinus rhythm was restored. The rest of the patient's hospital course was uneventful. A vasovagal reflex due to the operative procedure, anesthetic medications, and undiagnosed underlying heart disease could be considered for the possible etiology.