A 65-year-old woman with pulmonary fibrosis had hemodynamic instability develop after single lung transplantation. Transesophageal echocardiography was useful in determining the cause of hemodynamic instability, which was secondary to thoracic tamponade. Furthermore, transesophageal echocardiography monitoring was important in the decision to initiate extracorporeal membrane oxygenation to evaluate adequate positioning of the cannula and in the extracorporeal membrane oxygenation weaning process.