Unilateral re-expansion pulmonary oedema is a rare threatening complication of the treatment of lung atelectasis, pleural effusion or pneumothorax, the pathogenesis of which is not completely known. The clinical picture varies considerably from asymptomatic radiological findings to dramatic respiratory failure with circulatory shock. There are few literature reports of the treatment of re-expansion pulmonary oedema with non-invasive continuous positive airway pressure. We present the case of a 75-year-old man who presented in our emergency room with a large left-sided spontaneous pneumothorax and developed severe respiratory failure and circulatory collapse after drainage via a chest tube. The diagnosis of unilateral re-expansion pulmonary oedema was made and he was successfully treated with non-invasive continuous positive airway pressure. Literature data about the aetiological and pathogenetic factors of the condition are also considered.