A prothrombotic state caused by a deficiency of protein C or protein S, each an inhibitor of coagulation cascade, increases the risk of ischemic cerebrovascular accident (ICVA) in young adults, This retrospective review studies the relationship of protein C or S deficiency with childhood ICVA, From 1989 to 1995, 37 children were diagnosed by neuroimaging with ICVA unrelated to any known preexisting diagnosis, Protein C deficiency or protein S deficiency was the only identified risk factor for 5.4% (2 patients) and 13.5% (5 patients), respectively, of these 37 children, The data suggest that protein C or protein S deficiency is an important risk factor of ICVA in children. (C) 1997 by Elsevier Science Inc. All rights reserved.