A relatively high incidence of malignant hyperthermia (MH) and an unpredicted (usually increased) sensitivity to muscle relaxants are reported in patients with congenital myopathies (CM). We present a case of anesthetic management of a patient with a clinical diagnosis of CM. An 18-month-old, 11.3-kg, male patient, who had received a diagnosis of CM, was scheduled for the laparoscopic cryptorchidpexy. Anesthesia was induced with propofol and fentanyl, and the trachea was intubated without muscle relaxants. An epidural catheter was inserted via the sacral hiatus, the tip of which was located at the second lumbar level for a purpose of obtaining not only pain relief but also muscle relaxation. Anesthesia was maintained with propofol, nitrous oxide and fentanyl, combined with epidural anesthesia. The anesthetic course was uneventful with enough pain relief and good muscle relaxation.