Bile mud tends to develop into stones after a few months, so it is considered to be a pre-presentation of gallstones. Therefore, stones are more serious than bile sludge. Bile mud is a deposit of sediment-like material in the gallbladder, which is hypothesized to be a precursor to the formation of gallstones, and is characteristically seen on abdominal ultrasound. The recognized causes for the production of bile sludge are: decreased gallbladder motility, biliary sludge, and hypersecretion of mucin. It is commonly seen in extrahepatic bile duct obstruction, acute and chronic cholecystitis, prolonged fasting, and postoperative cholestasis. Current data indicate that the final fate of bile sludge has three directions: bile sludge dissipates on its own, which is more common; it is fluctuating, with disappearance and reappearance recurring, which is most common; and bile sludge may also form stones. In summary, stones are more serious than bile sludge.