Abstract A COMMON drug for pain and fever reduction is the compound, aspirin (acetylsalicylic acid). Acetyl-p-aminophenol (APAP), although not used as commonly as is aspirin, is a more potent antipyretic and analgesic drug. It is not possible to successfully measure pain in chickens, but it is possible to record changes in body temperature. Glick (1962) reported that low levels of aspirin (0.07% and 0.15%) did not affect body weight in chickens. In later research, Glick (1963) found that feeding acetylsalicylic acid for 5 or 56 days did not influence normal body temperature. However, when birds were subjected to a sudden rise in environmental temperature, the cloacal temperature of heat-stressed birds fed aspirin was lower than the cloacal temperature of the control birds. The literature reports no trials in which APAP (acetyl-p-aminophenol) was fed to chicks. The purpose of this experiment was to determine the effects of APAP on heat-stressed chickens. Since . . .