In five patients suffering from recurrent thrombosis and/or fetal death, a lupus anticoagulant was associated with a renal vasculopathy. Ischaemic episodes also involved the skin, heart, eyes and/or central nervous system. All patients were hypertensive. Two had renal insufficiency, two had non-nephrotic proteinuria, and in the last patient renal cortical ischaemia was detected by a tomographic scan in the absence of proteinuria. Renal biopsy showed thrombosis and/or intimal fibrosis of intrarenal vessels, and normal or ischaemic glomeruli without proliferative lesions. High-titres of anticardiolipin antibodies were found in 3 of 3 cases, and persisted after steroid therapy even if the circulating anticoagulant factor disappeared. All patients received corticosteroid therapy, alone or in combination with immunosuppressive drugs; two patients had prolonged oral anticoagulation, but thrombotic episodes recurred after stopping the drug. One patient died; the remaining four survived 18 months to 11 years after diagnosis, with stable chronic renal insufficiency in one of them. These results show that a lupus anticoagulant may be associated with prominent renal vascular disease, in the absence of proliferative glomerular lesions, and suggest that continuous anticoagulation may be beneficial in these patients.