The significances of analyzing bronchoalveolar lavage fluid (BALF) were studied using a steam inhalation injury model. Bronchoalveolar lavage was carried out at 1 and 5 h after steam inhalation injury. The parameters investigated included cellular analysis, the total protein content, malondialdehyde (MDA) content, the activity of superoxide dismutase (SOD), and the angiotensin converting enzyme (ACE) in the BALF, and pathologic examination of lungs. The study indicated that some informations of the pathophysiological changes in the lungs after inhalation injury could be acquired by the BALF analysis.