The objective of this study was to evaluate the pharmacokinetic profile of enrofloxacin and its active metabolite, ciprofloxacin, in Korean catfish after intravenous and oral administrations. Enrofloxacin was administered to Korean catfish by a single intravenous and oral administrations at the dose of 10 mg/kg body weight. The plasma concentrations from intravenous and oral administrations of enrofloxacin were determined by LC/MS. Pharmacokinetic parameters from both routes were described to have a two-compartmental model. After intravenous and oral administrations of enrofloxacin, the elimination half-lives (t(1/2,beta)), area under the drug concentration-time curves (AUC), oral bioavailability (F) were 17.44 +/- 4.66 h and 34.13 +/- 11.50 h, 48.1 +/- 15.7 mu g(.)h/mL and 27.3 +/- 12.4 mu g(.)h/mL, and 64.59 +/- 4.58% respectively. The 3.44 +/- 0.81 h maximum concentration (C-max) of 1.2 +/- 0.2 mu g/mL. Ciprofloxacin, an active metabolite of enrofloxacin, was detected at all the determined time-points from 0.25 to 72 h, with the C-max of 0.17 +/- 0.08 mu g/mL for intravenous dose. After oral administration, ciprofloxacin was detected at all the time-points except 0.25 h, with the C-max of 0.03 +/- 0.01 mu g/mL at 6.67 +/- 2.31 h. Ciprofloxacin was eliminated with terminal half-life t(1/2,beta) of 52.08 +/- 17.34 h for intravenous administration and 52.43 +/- 22.37 h for oral administration.