Stiff-man syndrome is a well-described, but rare and often overlooked, neuromuscular syndrome of rigidity, spasm, and gait abnormality that is associated with several endocrinologic and autoimmune disorders. A patient exhibiting many typical features of stiff-man syndrome had intermittent symptoms for 22 years before the correct diagnosis was made. Similar to many described patients, she was diabetic, hyperthyroid, and had elevated islet cell, antithyroid, and glutamic acid decarboxylase antibody levels. The high frequency of diabetes mellitus among patients with stiff-man syndrome is emphasized, as is increasing evidence to suggest that elaboration of anti-glutamic acid decarboxylase and anti-islet cell antibodies may play a role in the pathophysiologic state of the disorder.