Spontaneous rupture of the diaphragm during normal labour is extremely rare. It requires emergency surgical correction. The authors report what they believe is only the second reported case. Eleven hours after delivery of a male infant, a 27-year-old woman experienced severe epigastric pain, vomiting and dyspnea, followed by cardiopulmonary arrest. Although the ruptured diaphragm was diagnosed and repaired, she suffered severe anoxic encephalopathy and died 3 weeks after operation without regaining consciousness. Clinicians must be aware of the existence of this rare condition because failure to diagnose and treat the ruptured diaphragm will almost certainly lead to the patient's death.