Pulmonary complications including chest infections, atelectasis, pulmonary hypoplasia and ventilatory failure are the leading cause of death in the muscular dystrophies and atrophies. Ventilatory insufficiency is virtually inevitable in Duchenne muscular dystrophy and type 1 spinal muscular atrophy (SMA), but more variable in limb-girdle, congenital, and facioscapulohumeral muscular dystrophy. A cardiomyopathy may complicate Duchenne, Becker, and Emery-Dreifuss muscular dystrophies. Most patients respond well to ventilatory support with reduced pulmonary morbidity and extended survival. Careful monitoring and anticipation of complications are important so that ventilatory assistance can be started in a timely fashion.