A 42-year-old woman with myotonic dystrophy underwent general anesthesia twice. In the first operation, muscle rigidity was recognized when the patient was placed on lithotomy position under anesthesia with thiopental and nitrous oxide. In the second operation, rigidity was not observed under vecuronium, sevoflurane-nitrous oxide anesthesia. Neuromuscular monitoring of this patient did not show any difference of neuromuscular blockade with vecuronium compared with other 9 normal patients. We conclude that vecuronium and sevoflurane can be used safely in a patient with myotonic dystrophy under neuromuscular monitoring.