This family is the tenth reported world-wide and the second reported in Europe. Two of 3 brothers, their mother and probably their maternal grandmother were affected. METHODS paroxysmal bouts of ataxia and dysarthria, nystagmus of permanent gaze, the dominant autosomal transmission, the benign nature of the affection and the remarkable efficacy of acetazolamide were typical of familial paroxysmal ataxia. Specific points emphasized are the presence of a mild pyramidal syndrome as a permanent finding in 2 of these patients, and the anomalies of visual (longer lag period) and somesthetic (slowed conduction rate in the lemniscus medialis) evoked potentials probably the result of extension into other pathways than the cerebellar system. The finding of some degree of glucose intolerance, noted previously (Aimard, Vighetto et al., 1983) raises the question of the place of this disease in the group of paroxysmal ataxias due to pyruvic metabolism disorders.