Pharmacokinetics and elimination of florfenicol and florfenicol amine in grouper held in sea water at 23.3 AE 0.8°C were studied using HPLC method after they were given a single peroral dose of florfenicol at 24 mg kg À1 body weight. Florfenicol was rapidly absorbed from intestine and distributed extensively to all the tissues examined. The maximum concentrations (C max , lg g À1 or lg mL À1 ) in plasma and tissues were observed at 2-6 h (the time to reach maximum concentration, T max ) except for bile (T max = 24 h) and were in the order of intestine (52.02 AE 25.07) > bile (49.41 AE 28.16) > gill (45.12 AE 11.10) > plasma (28.28 AE 5.43) > liver (21.97 AE 12.08) > muscle (21.63 AE 6.12) > kidney (20.88 AE 11.28) > skin (19.10 AE 5.88). The drug distribution level was higher in plasma than in extravascular tissues except for bile, based on the ratios of the area under concentration-time curve between tissue and plasma (AUC tissue/plasma ). The elimination of florfenicol was rapid in fish, and the corresponding half-lives (T 1/2b ) in the order of magnitude were bile (13.92 h) > muscle or liver (12.31 h) > skin (11.77 h) > plasma (11.57) > gill (11.04 h) > intestine (10.55 h) > kidney (10.05 h). The delayed T max , lower C max and longer T 1/2b for florfenicol amine compared with florfenicol were measured in grouper.