Congenital abnormalities of the mitral valve may involve one or more components of the valve and may result in stenotic or regurgitant lesions. Mitral valve congenital anomalies can be found in infants, children, and adults. Stenotic lesions can be characterized as supravalvar (encircling rings), annular hypoplasia, valvar restrictions, and subvalvar conditions. Congenital regurgitant lesions can be characterized as annular dilatation, valvar deficiencies, chordal abnormalities, and papillary muscle anomalies. Operative techniques for mitral valve intervention are usually performed by median sternotomy, standard or mini right thoracotomy, or robotic technology. Complications associated with these specialized approaches for mitral valve repair will be discussed in this chapter.