OBJECTIVE: To recognize the clinical features of the bronchiolitis obliterans. METHOD: Clinical manifestation, chest X-ray, computed tomography (CT) and pulmonary function of 4 cases with bronchiolitis obliterans were retrospectively analyzed. RESULT: Two cases were after Stevens-Johnson syndrome (SJS), the other 2 were after severe pneumonia, including one suffered from adenovirus pneumonia. Cough, tachypnea and wheezing persisted in all the 4 patients. The symptoms lasted for at least 6 weeks, in one case for over one year. Crackles and wheezing were present in all the 4 cases. Hyperinflation was seen in chest radiographs in all cases. On pulmonary CT/high-resolution CT (HRCT), patchy opacity and bronchial wall thickening were seen in each patient. Areas of air trapping were seen in three cases. Bronchiectasis was seen in 2 cases, atelectasis and mosaic perfusion were seen respectively in one case. PO(2) was low in all the four cases. Wheezing was not responsive to beta(2) agonist and other bronchodilating therapy. Prednisone was used at a dose of 1 mg/(kg.d) in 3 cases. Two cases were followed up for 3 months. The clinical condition of one case was improved, whose wheezing and bronchiolar constriction disappeared, cough and dyspnea were also relieved. However, the condition of one patient was not improved, although the wheezing disappeared. The HRCT of these two cases showed no improvement. CONCLUSION: Clinical symptoms of BO were cough, tachypnea, and wheezing after acute lung injury. Crackles and wheezing were the most common signs in the BO. Chest radiographs showed hyperinflation. Pulmonary CT showed bronchial wall thickening, bronchiectasis, atelectasis, and mosaic perfusion. Pulmonary function tests suggested obstruction of small airway.