Abetalipoproteinaemia (Bassen-Kornzweig syndrome), an autosomal recessive inherited disease, up to now has been described in 53 instances in the world literature. Neurological symptoms were reported in 34 of them. Ataxia, loss of proprioceptive sensation, and areflexia characterize this disorder, resembling Friedreich's ataxia. Other signs, which may be inconstantly found, are weakness, diminution of cutaneous sensation, and in the later course an atypical retinitis pigmentosa. Laboratory examinations show acanthocytosis, lowered concentrations of serum cholesterol, triglycerides and phospholipids and as the pathognomonic feature of this disease absence of beta-lipoproteins. Reduced serum concentrations of fat soluble vitamin are secondary effects of this metabolic disorder. In a few cases there are connections to familial hypobeta-lipoproteinaemia, which is autosomal dominantly inherited. Therapeutic trials with a controlled dietary intake of fat may cause an improvement of clinical symptoms, additional doses of fat-soluble vitamin, if given during the early stages of the disease are said to prevent from retinopathy but do not seem to influence the development and course of neuropathy.