EDITOR,—Cardiolipin antibodies have been variously cited as a risk factor for cerebral thrombosis1 2 or splanchnic venous thrombosis,3 or as an epiphenomenon loosely associated with vascular disease.4 Cardiolipin antibodies seem to represent a family of low affinity antibodies which share a limited ability to bind to bovine cardiolipin. This rather artificial assay system, dependent on the binding of a low affinity human autoantibody to a non-primate, cross reacting substract of unproved relevance, can lead to some rather bizarre comparisons. Cardiolipin antibodies are probably identical to the chronic biological false positive Wasserman reaction described more than two decades ago in relation to systemic lupus erythematosus …