A 46-year-old male developed a fever of 38 degrees C and general fatigue, and two days later dysesthesia of limbs and muscle weakness of upper extremities appeared. He had difficulty in walking because of truncal and limb titubation and was admitted to our hospital. On admission, pin-prick and soft-touch sensation was reduced in the distal portion of all four extremities, and mild muscle weakness of limbs was noted. He also presented marked disturbance of vibratory and position sense, and had sensory ataxia. All deep tendon reflexes were absent. Moderate liver dysfunction was noted and serum IgM-HA antibody was positive. CSF total protein was elevated to 123 mg/dl on admission. Motor conduction velocity was mildly delayed in the lower extremities, and sensory conduction velocity was mildly delayed in the ulnar nerves and the left sural nerve. The serum of the patient had low titer of IgG anti-sulfated glucuronyl paragloboside (SGPG) antibody. The biopsy specimen from his right quadriceps femoris muscle showed subsarcolemmal aggregates of abnormally enlarged mitochondria with paracrystalline inclusions by electron microscopy. After admission neurological symptoms worsened. Severe diturbance of deep sensation and severe sensory ataxia persisted for a month and slowly improved thereafter. CSF total protein was elevated up to 760 mg/dl. He was treated with plasmapheresis of 12 times and was discharged on the 176th day after the onset, but he could not still walk by himself at that time. Diturbance of deep sensation still remained for one and a half years after the onset. Guillain-Barré syndrome (GBS) associated with acute hepatitis A is rare. In addition, there have been no previous reports describing abnormal mitochondrial changes of the skeletal muscle in GBS.