Since the beginning of the era of modern medicine, students have been taught that disease of the gallbladder is an affliction of the middle or later years of life. All physicians have heard variations of the "fair, fat female of 40." It is well to indoctrinate medical students with such easily remembered maxims, but this particular aphorism is better forgotten, for it can lead to serious error. As an example, it was not unusual to read in the histories of the cases of gallbladder disease in the adolescent and young adult that are reported, "Age of patient against the diagnosis of cholecystitis, but.... " An effort was made to estimate as closely as possible the occurrence of disease of the gallbladder in adolescents and young adults seen in a community the size of Rochester, Minn., which has a population of approximately 30,000. METHODS The records of all permanent residents of Rochester