Spontaneous native aortic valve thrombosis is an uncommon event occurring after heart valve disease, during cardiac catheterization, bacterial endocarditis, or as a hypercoagulative state as in antiphospholipid antibody syndrome. We report the case of a 55-year-old woman in whom thrombi developed on a native aortic valve with no predisposing cause. The thrombi were responsible for recurrent lower limb ischemia. Eighteen months after aortic valve replacement, the patient is doing well.