SUMMARY The pharmacokinetics of gentamicin, including half-life, apparent volume of distribution, total body clearance, and fraction of drug absorbed from im injection sites, were determined in 3 species of birds of prey (red-tailed hawks, great horned owls, and golden eagles). Significant differences (P < 0.05) between species were found for the half-life and total body clearance values for this broadspectrum antibiotic. The values for apparent volume of distribution and fraction absorbed did not differ among species and were similar to those reported in mammals. Rapid and relatively complete absorption from im injection sites resulted in high bioavailability. After TV administration of 10 mg of gentamicin/kg of body weight, serum concentrations > 12 μg/ml were present for at least 2 hours and > 2 μg/ml for 4 to 6 hours. On the basis of the various determinations, an im dose of 2.5 mg of gentamicm/kg given every 8 hours should provide therapeutic serum concentrations of gentamicin in the 3 species.