The most recently characterized genetic defect contributing to venous thrombophilia is the 20210 A prothrombin gene mutation. We describe a patient with this defect who had arterial thrombosis resulting in considerable mesenteric ischemia. Several environmental factors, which might otherwise be considered of low thrombotic risk, may also have contributed to her condition. The recognition of the potential for novel presentations of hypercoagulable states may contribute to a reduction in the morbidity associated with acute mesenteric ischemia.