Three non-steroidal anti-inflammatory drugs (NSAIDS), flunixin, ketoprofen and carprofen, were used in conjunction with ceftiofur, in the treatment of naturally occurring bovine respiratory disease. Sixty-six mixed-breed beef cattle weighing on average 197 kg met the inclusion criteria of pyrexia of at least 40°C, an illness score indicating at least moderate illness and at least moderate dyspnoea. They were allocated randomly to four treatment groups. All the groups received ceftiofur for three days at a dose rate of 1.1 mg/kg by intramuscular injection, and three groups received, in addition, a single dose of either flunixin (2.2 mg/kg by intravenous injection) or ketoprofen (3 mg/kg by intravenous injection) or carprofen (1.4 mg/kg by subcutaneous injection). During the first 24 hours of the study, the pyrexia of the three groups treated with a NSAID was reduced significantly more than the pyrexia of the group treated with ceftiofur alone, and two and four hours after treatment the reduction in pyrexia was significantly greater in the groups treated with flunixin and ketoprofen than in the group treated with carprofen. There were no statistically significant differences between the four groups with respect to depression, illness scores, dyspnoea or coughing. There was less lung consolidation in the three groups treated with a NSAID than in the animals treated with ceftiofur alone, but the difference was significant only in the group treated with flunixin.