Anticardiolipin antibodies (aCL-IgG/IgM) and anti-β2-glycoprotein I antibodies (aβ2GPI-IgG/IgM) are laboratory tests included in the current classification criteria for definite antiphospholipid syndrome (APS). However, not all of these assays have been commercially available in Japan. We investigated the efficacy of aCL-IgG/IgM and aβ2GPI-IgG/IgM assays using fluorescence enzyme immunoassay (Phadia:EliA(TM)) for the diagnosis of APS in Japan. This study comprised 229 sera from patients (100 with APS and 129 without APS). The diagnosis of APS was made according to Sydney revised Sapporo criteria. EliA(TM)Cardiolipin and EliA(TM)β2-Glycoprotein (Phadia AB. Uppsala Sweden) were used to detect aCL IgG/M and aβ2GPI IgG/M, respectively. Sensitivity, specificity and area under the receiver operating characteristic curve (AUC) were as follows; aCL-IgG (45%, 94%, 0.80), aCL-IgM (20%, 94%, 0.54), aβ2GPI-IgG (33%, 98%, 0.88) and aβ2GPI-IgM (16%, 99%, 0.64) respectively. aCL-IgM, aβ2GPI-IgG or aβ2GPI-IgM were detected in 10 patients (18%) with aCL-IgG negative. The use of Phadia:EliA(TM)antiphospholipid antibodies assays improve the diagnostic yield of thrombotic risk in APS patients.