Lupus anticoagulant (LAC) is an acquired inhibitor of prothrombin activator complex, which probably interferes with the phospholipid portion. Characteristically, LAC prolongs the partial prothrombin time, but only slightly prolongs the prothrombin time. It is a paradoxical fact that LAC is characterized by thrombosis. It was initially described in patients with SLE, but recently, it has been described as occurring with other autoimmune disorders. Patients with LAC have been treated with steroid and aspirin, anti platelet agents or warfarin. Steroid and aspirin therapy has been reported useful for habitual abortion associated with LAC. In our study, 11 patients, whose prior pregnancies resulted in habitual abortion (41 abortions), received intentional prednisolone (40 mg/day) and aspirin (81 mg/day) therapy before further pregnancies. The doses of both agents were decreased gradually, and the therapy with prednisolone (10-15 mg/day) and aspirin (40.5 mg/day) was maintained during the pregnancy period. The outcome of pregnancy was successful in 7 out of 10 pregnancies. To evaluate the relationship between LAC and glomerulopathy, we examined the renal biopsy from 5 LAC cases without SLE. In pathological findings, there were 3 of with mild proliferative GN and 2 cases of minor glomerular abnormality. There were no characteristic findings in LAC nephropathy.