A case of X-linked bulbar spinal atrophy (XBSA) was documented by clinical and genetic studies. The proband developed progressive muscle wasting of limb girdle, face and tongue accompanied by muscle fasciculation, minipoly-myoclonus of hands and mild gynecomastia over the past ten years. Facial myokimia was evoked by the trigger of a smile. Generalized hypo-reflexia was noted in all jerks. Studies of nerve electrophysiology revealed delay of distal latencies bilaterally over the median, ulnar and sural nerves combined with decreased amplitude of sensory nerve action potentials. Electromyogram study revealed high amplitude motor unit potential with giant waves in limb muscles. Studies of the expanded mutant allele of androgen receptor exon 1 revealed a 380 bp DNA fragment in the patient, in contrast to a 290 bp DNA fragment in a normal male. Fifty-two and 22 CAG triplet mutation were measured by sequence analysis in the patient and a normal male respectively. Sensory neuropathy, gynecomastia, mini-polymyoclonus of hands, and facial myokimia were the clinical characteristics of XBSA, especially in Taiwan. Phenotypic anticipation was also noted in the pedigree study.