A Review of the literature revealed only 18 cases of pneumocholecystitis. To these the following case is added. A. D., a 45-year-old colored female, was admitted to the hospital Jan. 20, 1951, acutely ill. Three days earlier, after her evening meal, she had experienced cramp-like abdominal pain followed by vomiting. The pain soon became localized to the right upper quadrant, slowly radiating to the right lower quadrant. Vomiting occurred at intervals. The bowels had not moved in the past two days. There was no history of previous attacks of this nature. The patient had had the usual childhood diseases. She had undergone an appendectomy in 1934, a total hysterectomy in 1935, a tonsillectomy in 1939, a subtotal thyroidectomy and excision of a cervical polyp in 1947. The family history was non-contributory. Physical examination showed abdominal distention with generalized tenderness more marked on the right, with muscle guarding. The temperature was subnormal. The clinical impression was acute cholecystitis. Other laboratory findings were normal. The patient ran a low-grade fever throughout the period of hospitalization, with one rise to 103° (R). Improvement was obtained on a regime of intravenous fluids, antibiotics, sedation, antispasmodics, and other supportive measures, and the patient was discharged about the fifteenth day, to return in six weeks for operation. Unfortunately x-ray examination was not ordered until eight days after admission. After this, films were obtained daily until discharge. On the initial roentgenograms a dilated pear-shaped gallbladder was demonstrable, containing gas or air, with pericholecystic air infiltration. The biliary duct system could not be identified at any time. A gastrointestinal series was negative. No fistulous tract could be demonstrated. Examination by the Graham method showed a pathological non-filling gallbladder. Duodenal drainage was instituted on the fourth day, the Miller-Abbott tube being placed in position under fluoroscopic control. Fractional specimens were collected and cultured, showing non-hemolytie streptococcus, E. coli, a yeast-likc fungus (contaminant?), and a Gram-positive rod. After the tenth day there was a diminution in the size of the gallbladder, which progressed rapidly. On the fifteenth day all the gas had been absorbed. The patient was readmitted for operation on March 12. Except for slight tenderness in the right upper quadrant, there were no significant findings. At operation the gallbladder was found to be sub-acutely inflamed, imbedded in massive adhesions, and removable with difficulty. Cultures of the contents revealed hemolytic staphylococci. Though the patient was moderately ill for about a week, the postoperative course was more favorable than had been expected. The gallbladder was dilated and the serosa inflamed. At the extreme end of the fundus was a perforation 1.0 cm. in diameter. The mucosa was redundant, green, and edematous (appearing to stand up in bubbles as if under pressure by gas).