Studies designed to elucidate the role of taste and postingestive factors in the rat's hyperphagic response to carbohydrate solutions are reviewed. Initial experiments revealed that polysaccharide solutions induce as much overeating as do sugar solutions, but that sugars and polysaccharides produce little or no overeating when presented in powder form. Although rats were found to be very attracted to the taste of polysaccharide solutions, as they are to sugar solutions, taste alone does not explain their overconsumption of these solutions. Several studies indicate that the postingestive actions of carbohydrates are also important determinants of carbohydrate appetite and intake. This is most clearly demonstrated by the conditioning of robust taste preferences using intragastric carbohydrate infusions.