Kaye, gallstones are common (about 20% of women in developed countries). There are several types of gallstones, the most frequent being cholesterol gallstones. These can occur due to an imbalance of cholesterol and the agents that are responsible for dissolving cholesterol, both secreted by the liver. If there's too much cholesterol or too little of the dissolving agents, stones can form. Anything that causes stones to more rapidly form, like decreased function of the gallbladder or even an individual's tendency to form stones, will lead to gallstones. Less common types of gallstones stem from too much bilirubin (the breakdown product of blood) or some intestinal diseases. Gallstones are more common as we age and in females, and also with hormone therapy. Despite the role of cholesterol in forming most gallstones, there's no relationship between stone formation and cholesterol in the blood. The majority of people with gallstones, fortunately, don't have symptoms. So as long as the gallstones don't cause problems, there's nothing to worry about and nothing that needs to be done.