Two patients presenting with pulmonary venous baffle obstruction following Mustard or Senning repair of transposition of the great arteries were successfully treated with percutaneous balloon dilatation. At the time of baffle dilatation, a significant systemic to pulmonary venous Mustard baffle leak was successfully closed with a Rashkind ductal occluder device. Specific features pertaining to the morphology of the baffle defect that allowed successful catheter occlusion are discussed and compared to that found in a Senning patient. The important adjunctive role of transoesophageal echocardiography within the catheterization laboratory is emphasized.