The diagnostic value of axilla skin biopsy has been investigated in a patient with adult polyglucosan body disease. The biopsy data have been compared with those of control subjects and with those from previously reported patients with Lafora's disease. In a patient with adult polyglucosan body disease and in patients with Lafora's disease, an abundance of polyglucosan bodies was found in the myoepithelial cells of the axillary apocrine glands. In the control group of subjects, polyglucosan bodies were only sporadically seen. Axilla skin biopsy is, therefore, an easy and reliable method for confirming the diagnosis of adult polyglucosan body disease.