Systemic lupus erythematosus (SLE) is associated with a poor pregnancy outcome. Antiphospholipid antibodies (APL), which include lupus anticoagulant (LAC) and anticardiolipin antibodies (aCL), are frequently found in patients with SLE, and their presence has been associated with fetal loss. To examine placental pathologic features of SLE patients with APL, we performed a pathologic study on 47 placental tissue samples from 47 pregnant SLE patients with APL (15 patients; four LAC single-positive patients, seven aCL single-positive patients, four LAC and aCL double-positive patients) and without APL (32 LAC and aCL double-negative patients). The incidence of extensive infarction, decidual vasculopathy, decidual thrombosis and perivillous fibrinoid change, which have been thought to be characteristic lesions of APL placenta, was significantly higher in the LAC and aCL double-positive patients than in the patients without APL. Conversely, the above-mentioned lesions between the LAC or aCL single-positive patients and the APL negative patients did not differ significantly. Among the 15 patients with APL, two of the three patients with both decidual vasculopathy and thrombosis had extensive infarction associated with fetal death. Moreover, the patients having fetal death showed LAC and aCL double-positivity. In conclusion, this study indicated that the LAC and aCL double-positivity is an important factor for extensive infarction resulting from decidual vasculopathy and decidual thrombosis in the SLE placenta. Moreover, it was indicated that LAC and aCL double-positivity is an important risk factor for fetal death in the SLE patient.