Hitiocytosis X, recently termed Langergans cell histiocytosis, is a rare disease histologically characterized by an abnormal proliferation of histiocytes, and of which the pathophysiology is still ambiguous. The clinical presentation is highly varied. Typically, there is a solitary or multiple bony involvements, and less frequently, lesions are found in other organs such as the lungs, liver, lymph nodes, skin, and mucosae. Interestingly, so far, there has been no report which shows multiple developments in both soft and hard tissues. In this report, we present a case of hitiocytosis X in both mandible and lung. This may provide some information for understanding the pathophysilogy of the histiocytosis X.