Sneddon syndrome is a rare systemic vasculopathy affecting the skin as livedo racemosa and the central nervous system as stroke. A 31-year-old man with a history of livedo racemosa presented with a partial left third nerve palsy. Skin biopsy showed signs of endotheliitis with obliteration of dermal blood vessels due to intimal proliferation and fibrin thrombi consistent with Sneddon syndrome. The patient was treated with platelet antiaggregant therapy with complete resolution of his third nerve palsy. Clinicians should be aware of Sneddon syndrome because prompt diagnosis and treatment may prevent potential morbidity and mortality.