Plasma and tissue drug concentrations were compared in eastern bobwhite quail (Colinus virginianus virginianus) and pigeons (Columba livia) given gentamicin by IM administration at the dosage of 10 mg/kg, and in greater sandhill cranes (Grus canadensis tabida) and hybrid rosybill ducks (Netta sp) given the same antibiotic at a dosage of 5 mg/kg. Quail and cranes had significantly higher liver concentrations of gentamicin at 6 hours after injection than did pigeons and ducks. Cranes had significantly higher plasma concentrations than did ducks at 6 hours after injection. Compared with plasma values, gentamicin concentrations were significantly higher in the liver of cranes at 12 hours after injection, and in the kidneys at 18 hours.