The deterioration of the respiratory function in children suffering from degenerative neuromuscular disease is the main cause of the high mortality rate associated with these diseases. Noninvasive ventilation (NIV) has reduced the morbidity and mortality due to respiratory insufficiency in these children. However, the use of support ventilation in some cases of spinal muscular atrophy (SMA) is still controversial. A retrospective study of 22 patients suffering from SMA who were followed up in the Paediatric Hospital of Coimbra is presented: 7 of type I, 11 of type II, and 4 of type III. In 17 of these cases, non-invasive ventilation by mask was begun, and in 3 of them NIV was applied for prophylactic purposes. The 7 children with SMA type I began NIV when they were 13 months of age on average (3 months-3 years); 5 of them died, between 1 and 15 months after the beginning of the ventilation. Of the 11 children with SMA type II, 8 were submitted to NIV and one died 22 months later. Three of the children in this group began NIV in a prophylactic way, and in all of them a decrease in the thoracic deformity was observed. Of the 4 patients of type III, 2 of them were submitted to non-invasive ventilation. In all of the symptomatic cases, a decrease in the frequency and severity of respiratory infections was observed, after ventilation was started. The respiratory support with NIV may improve the quality of life of children suffering from SMA as well as prolong their life expectancies. In SMA type I, whose clinical manifestations are precocious and whose prognostic is very serious, the application of this support has been debated.