A 32-year-old man with myotonic dystrophy underwent a thoracotomy for removal of a mediastinal thymoma. Pre-operative examination revealed features of myotonic dystrophy, the only other abnormality was mild restrictive pulmonary disease. Anaesthesia was induced with thiopentone and maintained with enflurane, nitrous oxide, oxygen and curare. Following surgery, the patient was mechanically ventilated for several hours and remained intubated for 9 hours. The anaesthesia and surgery were tolerated well; however, postoperative complications included refractory dysrhythmias, hypoxia, pneumococcal pneumonia and pulmonary emboli. More intensive preoperative pulmonary evaluation and physiotherapy coupled with more aggressive postoperative pulmonary care might have resulted in a smoother recovery phase.