Biliary calculi discovered radiographically within the alimentary tube are usually located either at the duodenojejunal flexure or at the ileocecal junction (1, 3, 4). An infrequent site for impaction of a gallstone has been the duodenal cap. A number of instances of this occurrence have been recorded at surgery and autopsy (5, 6), but rarely has the condition been roentgenographieally documented. Reports of only 4 cases with preoperative radiographic demonstration of a gallstone in the cap are available in the world literature (2, 5–7). So far as could be determined, none has heretofore been presented in the American literature. Case Report T. K., a white, Russian-Jewish housewife, aged 50, was seen in the Emergency Room of the Henry Ford Hospital the evening of Nov. 11, 1949, complaining of the sudden onset that day of severe epigastric pain and the vomiting of food and “greenish material.” This was the first such attack, although she had been troubled for some time by vaguely described upper abdominal distress and food intolerances. The patient was in acute distress. There was no jaundice. Tenderness was noted in the right upper quadrant. For a week the temperature spiked daily to 102°. Blood counts revealed a polymorphonuclear leukocytosis, with some counts as high as 20,000. Antibiotic and supportive measures weie followed by subsidence of fever and leukocytosis. Cholecystography, after priodax, showed no concentration of medium in the gallbladder. Roentgenograms and fluoroscopy revealed a normal stomach and duodenal cap (Fig. 1). The patient was discharged on Dec. 1, with the diagnosis of “subsided acute cholecystitis.” Followed in the outpatient department, she had only minor complaints. Surgery was advised but repeatedly refused. On the evening of May 13, 1951, the patient again presented herself at the Emergency Room, describing bouts of nausea and vomiting for a week. Again no jaundice was demonstrated and there was only slight upper abdominal tenderness. She was hospitalized and on May 17 passed, per rectum, a large, cholesterol gallstone measuring 2 cm. in diameter. Radiographic examination on May 18 showed a large speckled, oval, radiolucent defect, freely movable within the duodenal cap. Barium flowed past it into the descending portion of the duodenum. There was also a flow of barium through a short fistulous pathway into a small, irregular, contracted cavity in juxtaposition to the cap, presumed to be the gallbladder. This contained several small radiolucent shadows. The examination was repeated on May 23 and the findings duplicated. Review of the cholecystographic films of 1949, at this time, revealed a suggestion of calculus in the right upper quadrant (Fig. 2). In view of the known history of gallbladder disease, the passage per rectum of the calculus, and the obvious roentgen findings, a diagnosis was made of cholecystoduodenal fistula with calculus in the duodenal cap.