Ruggero Oddi: 120 years after the description of the eponymous sphincter: a story to be remembered.

This article presents a short account of theories, methods, and experimental data formulated and carried out 120 years ago, by Ruggero Oddi, then a 4th-year student in medicine, about the identification of the common bile duct sphincter. A historical picture emerges which leads us to think that Oddi not only discovered the bile duct sphincter, but also described bile duct dilation after cholecystectomy and performed biliary manometry for the first time. The role of serendipity and the almost unknown contribution of Arturo Marcacci, Oddi's "maestro" are also mentioned.