The use of enrofloxacin in elasmobranches for treatment of bacterial infections is becoming more popular in the public aquarium industry. Although dosages have been published for use of this drug in sharks, there have been limited pharmacokinetic studies cited. In this study, five leopard sharks were administered single doses of 10 mg/kg intramuscularly in the saddle region dorsal to the lateral line. One to two ml of blood was collected from each of the sharks at 6, 12, 24, and 48 hours post injection. Serum enrofloxacin concentration levels were determined via bioassay and the results were analyzed versus time. Peak serum concentrations were determined to be between six and twelve hours. The average concentrations for the 6, 12, 24, and 48 hour post collection times were 1.96, 2.06, 1.90, and 1.38 micrograms/ml respectively. Data showed all five sharks serum enrofloxacin concentrations met or exceeded 0.8 mcg/ml at the end of the 48 hour time period. From this data we estimate a dose of 10 mg/kg intramuscularly every 48 hours should be sufficient for most pathogenic bacteria.