We investigated the effects of early experience on sweet and sour preferences in children. Eightythree children were divided into four groups based on the type of formula fed during infancy and age. By using a forced-choice, sip-and-swallow procedure, we determined the level of sweetness and sourness preferred in juice. Children who were fed protein hydrolysate formulas, which have a distinctive sour and bitter taste and unpleasant odor, preferred higher levels of citric acid in juice when compared to older children who were fed similar formulas. No such difference was observed between the groups for sweet preference. However, the level of sweetness preferred in juice was related to the sugar content of the child's favorite cereal and whether the mother routinely added sugar to their foods. These data illustrate the wide variety of experiential factors that can influence flavor preferences during childhood.