Even though the incidence of corrosive esophagitis has been decreasing in the last decade, there are still a significant number of cases of suicidal ingestion of lye and acids in the adult and accidental ingestion in children in Korea. The purpose of this experiment is to study the histopathological changes in the lung which occur in the corrosive esophagitis experimentally produced by acetic acid. The esophagus of averaging two Kg. weighted rebbits were ingested with 3.0 cc of a 3.0% of acetic acid by the pipet through the esophagoscope, and the following macroscopic findings were observed. 1) Pulmonary congestion, bleeding thrombosis and edema are the initial findings which progress in intensity to the 3rd day. At this time bronchopneumonia set in. 2) At about I week they are followed with emphysematous changes in the lung which persist relatively for a long time. 3) At the end of the 5th week it shows relatively normal lung structure. From the above observations we can suggest a great amount of acid is absorbed directly into the blood stream and thus produces parenchymal damage in the lung which terminates in pneumonia. Further it can be stated that the symptoms which persist for a considerable length of time, are due to reabsorption of necrotic products from the stomach and intestine.