An enzyme linked immunoassay (ELISA) for the qualitative or semi-quantitative detection of IgG or IgM antibodies to Beta 2 Glycoprotein 1 (B2GP1) in human serum as an aid in diagnosis of autoimmune thrombosis in patients with Systemic Lupus Erythematosus (SLE) or lupus like disorders in conjunction with other laboratory and clinical findings.