This study was aimed at investigating the residual patterns of thiamphenicol (TP) in the cultured olive flounder (Paralichthys olivaceus) and black rockfish (Sebastes schlegeli) following oral administration. TP concentration were detected by high performance liquid chromatography with UV detector. The recovery rates of TP in serums ranged 77.05~97.23% (olive flounder) and 89.96~97.11% (black rockfish) for the concentration of 0.1, 1.0, 10 g/mL, respectively. After single administration of TP (100 mg/kg body μ weight) by oral route in olive flounder (700±50 g, 23±1.5 ) and black rockfish (500±30 g, 23±1.5 ), the ℃ ℃ concentration in the serum was determined at 1, 5, 10, 15, 24, 30, 50, 168, 264 and 432 h post-dose. Two-compartment model was applied to analyze in the pharmacokinetics of TP administered to the fishes. In the serum of olive flounder, TP was detected on 10 and 15 hours after treatment were 10.08 g/mL μ and 10.06 g/mL as maximum level, respectively. In the serum of black rockfish, TP was detected on 15 μ hours after treatment were 8.88 g/mL as maximum level. Concentrations of TP to the fishes were not μ measurable at 432 hours (18 days) after treatment in all samples. Similar residual patterns of TP were revealed between the fishes. These results are helpful for estimating withdrawal time of TP which has been already in use for farmed fish treatment.