BACKGROUND--Anticardiolipin antibodies, usually associated with vascular thrombosis in systemic lupus erythematosus, have been recently found associated with strokes in childhood, and acute adrenal hemorrhage in the adult. CASE REPORT--A 3 day-old fullterm newborn suffering from cerebrovascular ischemia and bilateral massive hemorrhage was found to have anticardiolipin antibodies detected during the neonatal period and 7 months later. There was no evidence of pathology in the mother or perinatal asphyxia. However, anticardiolipin antibodies were present in the mother 5 and 15 weeks after delivery. CONCLUSION--Association of anticardiolipin antibodies and vascular thrombosis has never been reported in the neonate. Persistence of such antibodies favor the hypothesis that they are not transmitted by the mother; they could represent an early manifestation of primary antiphospholipid syndrome.