We reviewed the clinical features of 5 cases of Langerhans' cell histiocytosis that had been referred because of pulmonary lesions. The most frequent symptom was persistent dry cough. Chest radiographs showed bilateral, symmetric reticulonodular infiltrates and accompanying cystic changes with an upper-field predominance. Pulmonary function testing (PFT) revealed moderate restrictive impairment in 3 patients. All the above features were in accordance with previous reports. The incidence of complications was, however, higher in the present cases than reported in the literature. Four cases were complicated with diabetes insipidus (DI), which caused polydipsia and polyuria on the initial presentation and was subsequently managed with intranasal desmopressin. In 4 cases, bone lesions were detected. A bone scintigram at 99mTc proved to be useful for surveillance. All patients had been followed up closely for longer than 2 years (median duration 2.8 years). Their clinical courses were generally stable without apparent decline in PFT, except that one patient with a psychiatric problem died from hypernatremia due to misuse of desmopressin. Immunosuppressive agents were given in only 2 patients including the one who died. Four transbronchial biopsies (TBB) were performed in 4 cases and at least 3 specimens were sampled from each. Histological diagnoses were made from TBB specimens in 3 patients, while the remaining 2 patients underwent an open lung biopsy. We conclude that TBB is acceptable as an initial diagnostic attempt. Multiple sampling may also contribute to preferable yield. Regarding patient management, we suggest that DI and bone lesions should be sought extensively as their incidence may be much higher than previously estimated.