Malignant hyperpyrexia is an inherited disorder of skeletal muscle characterized by intermittent hypermetabolic crises, usually triggered by anaesthetic agents. We present the case of a 19-year-old man who developed acute renal failure following an apparently uneventful general anaesthetic for appendicectomy. His renal failure was found to be secondary to rhabdomyolysis, and he made a full recovery after requiring haemodialysis for 14 days. Both the patient and his father were later discovered to have an underlying metabolic susceptibility to malignant hyperpyrexia. We propose that an undetected hypermetabolic crisis precipitated rhabdomyolysis and subsequent acute renal failure in this patient.