Nineteen patients with unilateral Ménière's disease, 20 with psychogenic dizziness, and 20 with recurrent vestibulopathy (diagnostic criteria in text of paper) were found to have normal five hour glucose tolerance tests, serum thyroxine and effective thyroid indices, and serologic tests for syphilis. Hypothyroidism and hypoglycemia were absent in all groups. An unexplained finding of each diagnostic group was significant increase of fasting blood glucose and insulin levels, and elevated insulin:glucose ratios, compared to a control group. There appears to be no diagnostic indication for performing these chemical and serologic studies in patients with unilateral Ménière's disease, psychogenic vertigo, or recurrent vestibulopathy. Reasons are given to support the view that recurrent vestibulopathy may be a specific vestibular disturbance.