A patient with Schmidt's syndrome and atypical symptoms of Addison's disease is presented. Autoimmune thyroiditis was diagnosed at the age of 12 years and then at 15 years; a diagnosis of migraine was made following 10 days of headache, visual field defects and dysarthria. One week later the patient was admitted to hospital in critical condition. Addison's disease was diagnosed and replacement therapy was introduced which brought about a rapid clinical improvement. Positive adrenal autoantibodies confirmed the diagnosis. We suggest that patients with organ-specific autoimmune disease undergo annual screening for adrenal activity, and in the event of abnormal results, adrenal autoantibody evaluation should be carried out, to avoid a life-threatening crisis caused by Addison's disease, which is often difficult to recognize due to atypical clinical presentation, as in the patient reported here.