The incidence of acute appendicitis and the total number of appendectomies performed in the adult population admitted to our medical center are both decreasing. The cause is not clear. Better nutrition and the wide-spread use of antibiotics are two possible factors which come to mind, but we know of no scientific evidence that these are responsible. There has been a slight decrease in the mean dietary fiber content in the Swedish diet during the last three decades. The decreased incidence of acute appendicitis cannot therefore be correlated with an increase in the mean dietary fiber intake.