Seventeen-day-old rat pups received intraoral infusions of two novel flavors, coffee (.625% w/v Sanka, decaffeinated) and saccharin (.5% w/v), of which one (CS+) was paired with a .75% body weight, i.p. injection of 0.4 M LiCl, and the other (CS-) was presented alone. On the following day, two more infusion tests were conducted to determine intake of each flavor. Intake of the CS+ flavor was markedly suppressed relative to that of the CS- flavor, although the magnitude of this effect depended on which flavor was designated CS+ and on the order in which CS+ and CS- were presented on the test day. These results indicate that preweanling rats are capable of discriminative taste aversion learning. The simple conditioning procedure should provide a useful method for studying the sensory development of the gustatory system and/or the developmental psychobiology of learning and memory. (Copyright (c) 1990 Psychonomic Society, Inc.).