OBJECTIVE: Appropriate antituberculosis chemotherapy may not prevent occurrence or progression of tracheobronchial stenosis and obstruction in the patients with endobronchial tuberculosis. The effect of corticosteroid treatment combined with antituberculosis chemotherapy was inconclusive. We evaluated prospectively the effect of corticosteroid treatment. METHODS: We diagnosed endobronchial tuberculosis by bronchoscopic examination and bronchial biopsy in the patients of tuberculosis within one month of antituberculosis chemotherapy. After randomization, we prescribed isoniazid, rifampin, ethambutol, and pyrazinamide with or without prednisolone 40 mg for 4 weeks. We carried out bronchoscopy in second month and ninth month of treatment. RESULTS: Edematous endobronchial tuberculosis showed significant improvement of bronchial stenosis after corticosteroid treatment(p<0.05). Corticosteroid treatment did not have advantage of improvement of bronchial stenosis in the patients with infiltrative endobronchial tuberculosis. CONCLUSION: Corticosteroid is effective in the treatment of bronchial stenosis when endobronchial tuberculosis is edematous type, in the early period of antituberculosis chemotherapy.