Mitochondrial myopathies are a group of diseases characterized by metabolic defects at the mitochondrial respiratory chain level which result in impaired oxidative phosphorylation and ATP synthesis. As with other neuromuscular diseases, respiratory muscles can be affected and ventilatory failure may occur. There have been isolated case reports of pregnant patients with ventilatory failure due to neuromuscular diseases such as polio and spinal muscular atrophy. We describe the case of a 34-year-old patient with mitochondrial myopathy and ventilatory failure requiring non-invasive ventilation who carried two pregnancies to term with no complications. We have not found a similar case in the literature.