Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the degeneration of upper and lower motor neurons. The disorder causes muscle weakness and atrophy in airway muscles including pharyngeal, laryngeal and other respiratory muscles. The response to muscle relaxant is also altered in patients with ALS. Because of the inherent muscle weakness and associated respiratory insufficiency, particular attentions are needed in anesthetic management of ALS patients. We used proper doses of inhalation anesthetics and opioids under EEG-entropy (electroencephalography-entropy) -monitoring without the use of muscle relaxants in the anesthetic management of a patient with ALS. The patient early recovered and was discharged on the same day without any respiratory complications.