The present study was planned to investigate the pharmacokinetics of ceftriaxone in experimentally induced febrile buffalo calves (n = 5). The fever was induced by intravenous injection of E.coli lipopolysaccaride (1 microgram/kg). To study the pharmacokinetics, ceftriaxone was administered at the dose rate of 10 mg/kg body wt. in all animals. At 1 min, the peak concentration of ceftriaxone was 79.4 +/- 2.37 microgram/ml and the drug was detected up to 6 h. The elimination rate constant was 0.35 +/- 0.02 /h and elimination half-life was 2.04 +/- 0.14 h. The apparent volume of distribution (Vd(area)) and total body clearance (ClB) were 1.21 +/- 0.15 l/kg and 0.41 +/- 0.03 l/kg/h, respectively. To maintain a minimum therapeutic concentration of 1 microgram/kg, a satisfactory dosage regimen of cefriaxone in febrile buffalo calves is 19 mg/kg followed by 18 mg/kg at 8 h intervals.