Three ambulant males with multicore myopathy, a rare congenital myopathy, are reported with nocturnal hypoventilation progressing to respiratory failure at the age of 9, 13, and 21 years. Deterioration in these individuals occurred over several months without any precipitating event. Patients had clinical evidence of nocturnal hypoventilation with hypoxaemia and hypercapnia. Forced vital capacity was significantly reduced (20 to 43% of predicted level). These parameters improved on institution of overnight ventilation using a BiPAP pressure support ventilator with face mask or nasal pillows with O2 saturation maintained above 90% overnight and an increase in forced vital capacity by as much as 100% (0.3 to 0.6 litres). This was matched by a symptomatic and functional improvement. Also present in these patients and not previously reported is the association of multicore myopathy with paraspinal contractures which produce a characteristic scoliosis described as a ‘side-sliding’ spine. This may be improved by spinal bracing or surgery.