Trichloroethylene elicits acute pulmonary cytotoxicity in mice, which involves Clara cells of bronchioles. In this study, we have examined the effects of an acute dose of trichloroethylene in lungs of mice over 3 months. Pulmonary fibrosis was first detected at 15 days and was progressive with time elapsed after trichloroethylene exposure. Diffuse interstitial fibrosis was observed in the alveolar zone, resulting in thickening of alveolar septa and distortion of lung structure. The fibrosis was most pronounced at 90 days after treatment, resulting in deposition of connective tissue in the alveolar septa. Levels of total lung hydroxyproline were not significantly different in control and treated mice at 30 and 60 days after trichloroethylene treatment, but were significantly increased at 90 days. Proline content remained unchanged during the course of this study. The increase in collagen deposition at 90 days coincided with a significant increase in lung elastic recoil. Our results show that a single acute dose of trichloroethylene causes structural and functional abnormalities that are progressive for at least 3 months.