A high performance liquid chromatograpic methcd for determination of oxytetracycline (OTQ and cMortetr&tyciine (CrQ in prawn and eel fJs has bten developed. It could obtain good seration and linear calibtation curves of OTC and crc when eing chronatographed on Chrornosper C8 glass column and mobile phase consistng of MDH-CH CN-0.O1M Olic acid. Three sulfa dngs, 3 antibiotics and 3 synthetic kacteriocides did&t interfer the detution. The procedure involved double extraction with pH 2.0 and pH 4.5 Mdllvain buffers and cleanup on a Sep-Pak Cl 8 cartridge. Recoveries of OTC and arc in prawn feeds 1(0.1-101.2% and 94.6-97.5% and 87.1-92.5% and 80.0-82.9% for eel fs, respectively.