Operations for inflammatory and calculous disease of the extrahepatic biliary tract are among the most frequent in abdominal surgery. Despite this, the timing of such procedures during the natural history of cholecystitis and choledocholithiasis remains controversial. For example, some authorities feel that routine intervention early in the acute course of cholecystitis is justified.1-3 Others prefer to postpone operation until a symptom-free interval has existed.4,5 The usual practice at Washington University-Barnes Hospital has been to delay operation where possible until the acute symptoms and signs of cholecystitis and choledocholithiasis have subsided. This study was undertaken in an effort to assess the wisdom of this practice. Coincident to this assessment was an evaluation of the effect, if any, of incidental appendectomy at the same time as cholecystectomy upon morbidity. Clinical Material Primary operations upon the biliary tract were performed upon 1,000 patients in the Barnes Hospital between January 1962 and