SATISFACTORY surgical management of acquired mitral valve disease requires optimal operative exposure. The increasing frequency of open reoperation following closed techniques and the high incidence of multiple valve disease, make the left or right thoracic approach undesirable. An ideal incision allows a direct approach to the mitral, aortic, and tricuspid valves, and avoids troublesome adhesions from previous procedures. The ease with which the mitral valve cleft, associated with an ostium primum defect, can be visualized and repaired emphasizes the close proximity of this valve to the atrial septum. The proximity of the mitral valve to the base of the atrial septum affords an easy exposure through an incision in the septum (Fig 1). An anterior transatrial septal approach via a median sternotomy incision has been utilized to expose the mitral valve allowing satisfactory exposure of aortic and tricuspid valve areas as well. This approach permits any method of valvuloplasty as