Purpose: Bronchiolitis obliterans (BO), an uncommon chronic obstructive lung disease in children, is most often seen following a severe lower respiratory tract infection (LRTI). We investigated the clinical characteristics, etiology, possible risk factors, radiological findings, and response to treatment in children diagnosed with post-infectious BO. Methods: A retrospective study was performed on 62 patients diagnosed with post-infectious BO based on clinical and high-resolution computed tomography (HRCT) findings from 2005 to 2010. Forty-eight age-matched children who were admitted with the first episode of LRTI and did not subsequently develop BO were also studied as control subjects. Results: Median ages at diagnosis and initial insult were 28 and 17 months, respectively. The median duration from initial LRTI until diagnosis was 5 months. Children who developed BO showed more respiratory compromise during their acute episodes of LRTI than those who did not. Symptom severity score decreased significantly after adequate treatment, which was significantly greater in patients treated with pulse steroid therapy than those treated with other controllers. Conclusion: The results suggest that the development of post-infectious BO should be suspected in the children showing persistent respiratory symptoms after severe LRTIs. They also suggest that adequate treatment including pulse steroid therapy may improve clinical status and the prognosis of these patients. [Pediatr Allergy Respir Dis(Korea) 2011;21:156-164]