Introduction:Langerhans cell histiocytosis (LCH) refers to a group of rare reticuloendothelial system disorders and it occurs most often in young adults and children. A 57-year-old edentulous female patient who complained of dull pain in the posterior region of the mandible referred to the dental office, with a complaint of dull pain in the posterior region of the mandible. The lesion was diagnosed as LCH . Oral manifestations could be the first signs of Langerhans' cell histiocytosis . Therefore, t he dentist must be aware of the oral symptoms so in order that the disease is not overlooked .