In 1983, a detailed clinical description of a new syndrome was published. This prothrombotic syndrome was initially called the anticardiolipin syndrome and subsequently the antiphospholipid syndrome (APS), or Hughes Syndrome. Almost uniquely, it results in arterial as well as venous thrombosis and is marked by the presence of circulating antiphospholipid antibodies. Clinical features are protean, ranging from peripheral deep vein thrombosis (DVT) to involvement of internal organs such as the liver, kidneys, and adrenals. Likewise, arterial thrombosis can result in life-threatening infarction of organs such as the heart. The nervous system is frequently affected, with migraine, memory loss, balance disorders, stroke, and atypical multiple sclerosis being prominent. Other features include recurrent miscarriage, thrombocytopenia, and livedo reticularis. More recent observations have included ischemic bone fractures, renal and celiac artery stenosis, and a possible tendency toward accelerated atherosclerosis. The condition is seen in patients with lupus, but, significantly, occurs without associated lupus ("primary" APS)-indeed, increasing clinical recognition of Hughes Syndrome suggests that this condition will overtake lupus in prevalence. Treatment at present is by anticoagulation. The mechanisms for thrombosis are being worked out; it has been suggested that in some situations (e.g., pregnancy loss), an inflammatory component as well as thrombosis may play a part.