The Authors describe a case of neonatal hemorrhagic syndrome associated with a large hemangioma on the left lower limb with an unfavourable prognosis. The clinical, biohumoral and anatomicopathological characteristics indicate a Kasabach-Merrit syndrome (SKM) with massive platelet sequestration in the large hemangioma. The pathogenetical mechanisms of SKM and the medical surgical and radiant therapy are mentioned. The Authors also discuss the various diagnostic problems imposed by the presence of serious hemorrhagic pathology at neonatal age.