Animal models of the relatively new antiphospholipid syndrome (APS) enabled researchers to understand disease pathogenesis and to test novel experimental therapeutic modalities. Animal models of APS include spontaneous genetic models and experimental induced models. The latter test more reliably the pathogenicity of antiphospholipid antibodies because the syndrome is induced in normal mice rather than being secondary to a preexisting autoimmune disease. Reports about animal models of APS in the recent year provide new insights into the pathogenesis of antiphospholipid antibodies and β2-glycoprotein-I in reproductive failure, neurologic manifestations, thrombosis, and atherosclerosis. In addition, novel therapies that were successful in experimental APS included anti-idiotypes, oral tolerance, and specific peptides that bind to β2-glycoprotein-I. Animal models provide the first step in development of novel therapies for patients with APS. (C) 2000 Lippincott Williams and Wilkins, Inc.