It is well known that paraquat causes severe organ-toxicity and pulmonary damage. We observed the progress of a patient who survived paraquat poisoning, and we recorded the changes in the lung by high resolution CT. The patient was a 35-year-old man who attempted suicide by paraquat (Guramoxone 100 ml) ingestion. At the time of hospitalization, there was no respiratory involvement. Five days after ingestion, an X-ray examination showed only indistinct vascularity of both lung fields, but high resolution CT showed increased density in the central part of both lung fields. According to the clinical progress after ingestion, mediastinal and subcutaneous emphysema were noted by chest X-ray examination. On the other hand, severe interstitial pneumonia progression of severe lung fibrosis with a decrease in lung volume and interstitial pulmonary emphysema in addition to mediastinal, subcutaneous emphysema were seen by high resolution CT. High resolution CT is useful for detecting morphologic change and diagnosing clinical stages. Observing the course of changes by high resolution CT is useful for deciding the course of clinical therapy, and we have no hesitation in affirming that it should be used in such cases.