Recombinant mouse protein C was cloned, expressed, purified, and activated by Protac or thrombin. The anticoagulant activities of mouse and human activated protein C (APC) were compared using mouse and human plasma and the neuroprotective properties of murine APC were studied in an ischemic stroke model. Both human APC and mouse APC prolonged the activated partial thromboplastin time in a dose-dependent manner, but mouse APC was sixfold more effective than human APC as an anticoagulant in mouse plasma. Human protein S enhanced prolongation of the APTT clotting time of human plasma by human APC, but not by mouse APC. Hydrolysis of the S-2366 chromogenic substrate by murine APC was essentially identical to human APC. Mouse plasma contains 75 nM protein C. In a murine ischemic stroke model based on middle cerebral artery occlusion, murine APC was highly neuroprotective. The results show that recombinant murine APC is functionally similar to human APC both in vitro and in vivo and that it displays significant species specificity. The results imply that murine APC is notably superior to human APC for studies of murine disease models, including thrombosis and ischemic brain injury.