Rats undergoing laparotomy received either carprofen (5 mg/kg) or ketoprofen (5 mg/kg) administered orally in flavoured gelatin, or by subcutaneous injection. A control group that received no analgesic showed a significant (3 per cent) fall in bodyweight (P=0.009) after laparotomy. This decrease was greater than that seen in the groups receiving carprofen (P=006) or ketoprofen (Pd=0012) administered subcutaneously, which continued to gain weight following surgery. All animals showed a significant fall in food consumption but this decrease was greater in the jelly alone group (47 per cent) than in the group receiving carprofen (17 per cent) (P=0.015) administered subcutaneously. A significant fall in water consumption occurred in the control group (40 per cent) and in animals that received oral carprofen (13 per cent) or ketoprofen (22 per cent). No significant decrease was seen in groups receiving either carprofen or ketoprofen administered subcutaneously (P>0.1). This study shows that a relatively simple surgical procedure results in a major reduction in food and water consumption in rats. This reduction can be minimised by the administration of ketoprofen or carprofen (5 mg/kg subcutaneously), but higher dose rates are required if these drugs are to be administered by the oral route.