Primary pulmonary histiocytosis X is an uncommon interstitial disorder of unknown etiology characterized by atypical histiocyte infiltration forming nodular lesions. The clinical presentation of PHX is variable. The patient may stay asymptomatic with an ah' normal chest radiograph, may experience pneumothorax or advanced lung disorder with respiratory symptoms or nonpulmonary involvement such as central diabetes insipidus. Corticosteroids and cytotoxic agents are of limited value in the treatment of the disorder. In this article we presented a 3 5-year-old female patient with pulmonary histiocytosis X accompanied by diabetes insipidus.