Takayasu's arteritis (TA) is a rare, chronic, and idiopathic vasculitis of the aorta and/or its main branches. There have been case reports of this disease associated with immune hypercoaguable states, namely raised antiphospholipid antibodies. Investigations of the thrombotic nature of Takayasu's arteritis have shown elevated levels of B-thromboglobulin, platelet factor 4, thrombin-antithrombin III complex, and fibrinopeptide A. We report the first case of TA associated with the Factor V Leiden gene defect (Activated Protein C Resistance). The patient is a 30-year-old female who presented with six months of bilateral lower and upper extremity claudication, carotid artery tenderness, diminished brachial pulse and no measurable blood pressure in the left arm, an erythrocyte sedimentation rate (Westergren) of 62 mm/hr, and an angiogram meeting the clinical criteria for TA. Her symptoms showed a dramatic response to high-dose oral glucocorticosteroids and she was also maintained on long-term anticoagulation. This case illustrates that hereditary hypercoagulable states can coexist with acquired vasculitidies and that further investigation into these associations and their pathophysiologic interaction is warranted.