The authors report the case of an adult with cystic fibrosis (CF) presenting with an episode of acute shortness of breath during an inpatient stay for infective exacerbation of CF. The treatment of bronchodilators and steroids for presumed airways disease was not effective and on review of the chest x-ray, it showed some evidence of pulmonary oedema. An echo showed a dilated left ventricle and globally reduced function. Serology came back positive for enterovirus which was in keeping with a diagnosis of myocarditis.