Antibiotic usage is a vital component of veterinary medicine but the unique anatomy of some species can make administration difficult. The objective of this study was to determine the pharmacokinetic parameters of ceftiofur crystalline free acid (CCFA), a long-acting cephalosporin antibiotic, after parenteral administration in American flamingos (Phoenicopterus ruber). A dose of 10 mg/kg of CCFA was administered intramuscularly to 11 birds and blood was collected at various time points from 0 to 192 hr. Pharmacokinetic parameters for ceftiofur equivalents were determined and reached levels above minimum inhibitory concentrations of various bacterial organisms in other avian species through 96 hr in 9/11 birds. Based on these findings and comparison to other avian studies, ceftiofur crystalline free acid appears to be a long-acting antibiotic option for American flamingos. Administration of this antibiotic should be utilized in conjunction with culture and sensitivity of suspected pathogens.