The clinical evolution of mitral valve disfunction caused by papillary muscle necrosis in patients with anomalous origin of the left coronary artery from the pulmonary trunk was analysed in three children (one 42-day-old male, one five-month-old female and one seven-year-old female). Two patients had been submitted to surgical repair of the anomalous origin of the coronary artery; one of them without mitral repair had a bad evolution in the postoperative period, was reoperated for mitral valve replacement and died two days after surgery. The other patient with plastic of mitral valve had a good outcome. The data indicated that the surgical repair of mitral valve should be provided in cases of mitral valve incompetence secondary to anomalous origin of the left coronary artery from the pulmonary trunk.