X-linked recessive bulbospinal muscular atrophy (Kennedy's syndrome) is a variant of the spinal muscular atrophies caused by mutation of androgen receptor gene on X-chromosome. A 69-year-old man had suffered from slowly progressive lower extremity weakness and gynecomastia. Muscle weakness was more severe in proximal muscles and showed symmetrical features. He had fascicular contraction on his face and tongue. All tendon reflexes were absent and pyramidal signs were not detected. Nerve conduction studies were normal except low amplitude of sensory nerve action potential in median nerve. Needle electromyography revealed widespread chronic denervation potentials in all sampling muscles of extremities, facial and tongue muscles. Histopathologic findings showed chronic denervation atrophy. DNA analysis showed abnormal expansion of CAG repeats in the androgen receptor gene and we confirmed this case as Kennedy's syndrome. If an adult patient has slowly progressive muscle weakness, bulbar symptoms and signs of male genital failure, DNA analysis should be taken to differentiate Kennedy syndrome from other motor neuron disease or myopathy. (J Korean Acad Rehab Med 2002; 26: 626-630)
