Sneddon syndrome is an association of livedo racemosa and cerebrovascular ischemic events generally occurring in young adults. This is an uncommon chronic progressive arterio-occlusive disorder of unknown cause involving small and medium sized vessels. We report four cases. One case was disclosed by cerebral hemorrhage. One pathogenic hypothesis suggests the involvement of an idiopathic progressive inflammatory arteriopathy or secondary thrombotic disorder comparable with antiphospholipid syndrome.