Placement of a pulmonary artery catheter is associated with various complications, including catheter knotting. Fluoroscopy can be used to visualize and confirm catheter knotting. Transesophageal echocardiography is readily available to detect knot formation in the operating room or intensive care unit. We present a case in which pulmonary artery catheter knotting was detected by transesophageal echocardiography. This method may be useful in the operating room or in the intensive care unit to identify the presence and location of catheter knotting.