Cases in which the common bile duct empties into a duodenal diverticulum instead of the duodenum are apparently rare. The first report of such an occurrence was made by Baldwin (1) in 1911. In a review of the literature at that time he had discovered no similar instance. In a personal series of 15 diverticula in 14 duodenums, however, he found 4 specimens in which the common bile duct terminated in the diverticulum. It was not until 1931 that another case was reported, by Benninghoven and Michael (2). These cases were all discovered postmortem. The case reported below we believe to be the first in which entrance of the common duct into the diverticulum was shown roentgenographically. Case Report Mrs. A. R., a 61-year-old white woman, had been well until 1936, when she began to have episodes of right upper quadrant pain, jaundice, and loss of weight. In August 1941, cholecystectomy and choledochostomy were performed. The gallbladder was acutely inflamed, and stones were found in both the gallbladder and the common duct. Following surgery the common duct was drained by T-tube for sixteen days. The subsequent history was uneventful until April 1944, when symptoms similar to those prior to operation recurred. At a second operation, in November 1944, the common duct was explored. The choledochus was found to be moderately dilated and to contain many stones and sandy material. It was noted at the time of surgery that the little finger could easily be inserted into what was believed to be the ampulla of Vater. The common duct was again drained by T-tube for twelve days, and the patient remained in good health until June 1948. At that time she once more presented evidence of choledocholithiasis: colicky right upper quadrant pain, chills, fever, jaundice, nausea, vomiting, and weight loss. A choledochostomy was performed, and many stones were removed from the common duct, which was dilated to 1 cm. in diameter. Cholangiography was attempted at the time of operation but was unsuccessful. Postoperative cholangiograms, with 35 per cent diodrast, however, showed several small stones in the common duct. Repeat cholangiograms revealed a large collection of dye adjacent to the distal portion of the common duct (Fig. 1). Oral administration of barium showed this to represent a diverticulum of the second portion of the duodenum, into which the common duct emptied (Fig. 2). The cholangiograms and barium studies revealed a defect in the opaque medium in the diverticulum about the termination of the common duct. It was felt that this represented the papilla of Vater (Fig. 3). The patient was again operated upon in September 1948, because it was known that stones remained in the common duct. A few days prior to this operation, the T-tube which had been present since the previous surgery was inadvertently removed. When the incision was made, the stones were found in the sinus tract. The common duct was dilated.