Histiocytosis X is the abnormal proliferation of histiocytes and usually a massive aggregation of eosinophilic leukocytes. The clinical features and prognosises of subclasses of histiocytosis X depend on the severity and extent of the organ involvement. The subclasses include Letterer-Siwe disease(Acute disseminated histiocytosis X), eosinophilic granuloma, Hand-Schuller-Christian disease. Letterer-Siwe disease(acute, subacute form) refers to the form of disease that is most often fatal because of the widespread skeletal, extraskeletal lesion ; this usually affects infants and children less than 3 years of age. Eosinophilic granuloma(histiocytosis X, localized) refers to a chronic form of disease with skeletal lesion ; It usually affects children and young adult. Hand-Schuller-Christian disease(chronic form) refers to a chronic form of disease with skeletal, extraskeletal lesions. It usually affects children over the age of 3 years. In our hospital, 8 year old female patient visited complaining of hard swelling of mandibule body, left side and 6 year old female patient visited complaining of painful swelling of mandibular angle, right side. We diagnosed eosinophilic granuloma and curetted the lesiones and refered to Dept. pediatrics for chemotherapy. We present 2 cases to you with literatures.