A previously fit 12-yr-old boy, who had no previous history of anaesthesia, underwent general anaesthesia using isoflurane for an elective circumcision. After uneventful surgery and anaesthesia, he suffered a cardiorespiratory arrest in the recovery room. Prompt oxygenation and cardiopulmonary resuscitation (CPR) were instituted. The initial serum potassium was >13 mmol litre(-1) and prolonged CPR was required while potassium levels were reduced. Further investigation demonstrated a creatine kinase (CK) >70 000 U litre(-1) which was consistent with a diagnosis of rhabdomyolysis. Despite requiring CPR for 1 h 45 min and a prolonged intensive care admission for multi-organ failure, the child has made an excellent recovery, including normal cognitive function. Subsequent genetic analysis has shown that the boy has previously undiagnosed Becker's muscular dystrophy. We believe that the patient had acute rhabdomyolysis as a result of a volatile anaesthetic agent in association with an undiagnosed muscular dystrophy. In recent years, largely based on case report literature, there has been a shift in opinion as to the cause of such adverse perioperative events. What was previously thought to be malignant hyperpyrexia (MH) is now considered to be anaesthesia-induced rhabdomyolysis, an alternative and distinct reaction. The distinguishing feature of anaesthesia-induced rhabdomyolysis from MH is an acute rhabdomyolysis, without preceding hypermetabolism.