A 10-month-old female infant with congenital myasthenic syndrome suffering from acute respiratory failure was supported using face mask positive pressure ventilation until definitive diagnosis and specific treatment was achieved. A 12-year-old girl suffering from seronegative myasthenia gravis was treated by helmet-delivered noninvasive ventilation during recurrent myasthenic episodes. Noninvasive support was really beneficial in the myasthenic crisis with respiratory muscle weakness, whereas a shift to tracheal intubation was necessary when pulmonary infection and multiple atelectasis occurred. The new helmet interface for noninvasive positive pressure ventilation can represent a valuable means of respiratory support in the early phase of respiratory failure in older children.