This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. To the Editor:— The report of four cases of mediastinal emphysema in diabetic coma (208:2315, 1969) prompts us to present an additional example. Report of a Case:— A 16-year-old white male was admitted because of dyspnea and increasing drowsiness of one day's duration, in addition to progressive nausea and vomiting. The blood pressure was 130/80; pulse rate was 140 beats per minute; respiratory rate was 38; and temperature was 100 F (37.8 C). The patient was well developed and well nourished, but barely responsive and markedly cyanotic. Kussmaul respirations and flushed facies were evident. The pupils were dilated and the eyeballs were soft on palpation. The breath sounds were harsh but the lungs were otherwise clear. The heart sounds were distant. The abdomen was mildly rigid and no abnormal masses were present. At the time of admission, urinalysis revealed the following values: pH, 5.0; specific gravity, 1.035; glucose, 4+;