Several cases of association between cerebellar ataxia and hypothyroidism have been reported, in which cerebellar symptoms regressed after euthyroid state was obtained, suggesting an etiologic relationship between hypothyroidism and ataxia. We present a further case of hypothyroidism and ataxia, with a peculiar positive family history for both thyroid and cerebellar disorders. Long-term replacement therapy with L-thyroxine determined the regression of hypothyroidism; however, no improvement in cerebellar symptoms was observed. The lack of response of the neurologic symptoms to L-thyroxine treatment suggests the absence of an etiological relationship between thyroid disease and cerebellar disease in this case.