We report the case of a 40-year-old hypoxic encephalopathy patient who suffered from dry mouth and frequent poor oral hygiene secondary to a prominent nasolabial fold and elevated upper lip, exposing the canine teeth at rest. This expression was confirmed secondary to persistent contraction of the levator labii superioris muscle with electromyography (EMG) study. We have injected 6 units of Botulinum toxin A in levator labii superioris muscle with electromyographic guidance. Elevation of upper lip at rest causing exposure of canine teeth has been nearly disappeared 3 days after the injection. We suggest that chemical weakening of the levator labii superioris muscle using Botulinum toxin A could be possibly responsible for the dramatic reduction of elevated upper lip exposing canine teeth in patients with hypoxic encephalopathy.