A case is reported of unexplained unilateral thigh muscle atrophy and frequent falling with poor response to conventional conservative treatments in a patient with bipolar disorder who self-selected acupuncture treatment as a last resort. The patient experienced gradual improvements in lower extremity weakness and fewer falls during the 8-month treatment. No adverse event or aggravation of the bipolar disorder was observed. These outcomes suggest that acupuncture may be a feasible adjunct for reducing falling and restoring postural balances in patients with bipolar disorder.