Langerhans cell histiocytosis (LCH), previously known as histiocytosis X, is a rare idiopathic disorder of reticulo-endothelial system with abnormal proliferation of bone marrow derived Langerhans cells along with a variable number of leukocytes, such as eosinophils, neutrophils, lymphocytes and plasma cells. Three years old male child presented with multifocal osteolytic lesions and papulosquamous skin lesions. Clinical and radiographic features, such as severe alveolar bone loss, mobility of teeth, precocious eruption of teeth, floating appearance of teeth in orthopantomogram (OPG), osteolytic lesion in skull and cutaneous lesions were highly suggestive of LCH disease. Skin biopsy confirmed a diagnosis of LCH. Induction chemotherapy with oral prednisolone and intravenous vinblastine was started. Child responded well to chemotherapy. The clinical significance of the presented case is to diagnose the case of LCH on the basis of the manifestation of severe periodontal disease as this can be first or only manifestation of LCH. A dentist plays a major role in the multidisciplinary treatment of LCH through routine examination and periodic follow-up. How to cite this article: Bansal M, Srivastava VK, Bansal R, Gupta V, Bansal M, Patne S. Severe Periodontal Disease Manifested in Chronic Disseminated Type of Langerhans Cell Histiocytosis in a 3-Year Old Child. Int J Clin Pediatr Dent 2014;7(3):217-219.