Introduction This investigation was undertaken to demonstrate the degree of accuracy with which stones can be palpated in the extrahepatic biliary ducts. It was prompted by the following considerations: 1. Our clinical impression that palpation of the ducts, when carefully and thoroughly performed, is reliable for determining the presence or absence of stones. 2. A suspicion gained from reports in the surgical literature that this impression is not shared by many of our colleagues. Diffenbaugh and Strohl1state that "a stone can be palpated in approximately onefourth of those ducts containing stones." Waugh, Johnston, and Cain2found palpable stones in only 45 (25.7%) of 173 patients with common duct stones. 3. An opinion based on repeated observations that palpation of the biliary ducts, as commonly practiced, often is incomplete and restricted to the supraduodenal portions of the ductual system. This project was initiated in 1952, and the succeeding