Macrophage Activation Syndrome (MAS), or Haemophagocytosis Syndrome, is a clinical-biological entity characterized by the proliferation and non-specific activation of macrophages of the reticulo-histiocytic system, with phagocytosis of the blood elements formed. This syndrome can be primary in children or secondary to various conditions at any age. Its association with Hodgkin's lymphoma is exceptional. We report here a case of MAS that revealed Hodgkin's lymphoma in a 5-year-old child. And we underline the interest of an urgent diagnosis and a fast care because risk of evolution towards a fatal multivisceral failure.