A total of 221 (200-500 g/sample) of frozen raw shrimps (Penaeus monodon and Penaeus vanammei) samples from Sarawak's' processing plants were obtained from January to September 2007 for determination of chloramphenicol residues using Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). Out of 221 frozen shrimp samples examined, residues of chloramphenicol was detected in 183 samples (82.8%) ranging from 0.001-6.283 ng/ml. A total of 36 (16.3%) positive samples recorded level above the safety limit or MRPL (0.3 ng/ml) as proposed by the European Union for safe consumption. This study demonstrates that although banned, chloramphenicol might still being used in shrimp farms in Sarawak.Sejumlah 221 sampel (200-500 g/sampel) udang sejuk beku (Penaeus monodon dan Penaeus vanammei) dari kilang pemprosesan udang di sekitar Sarawak telah diperolehi daripada Januari hingga September 2007 untuk menentukan residu chloramphenicol di dalamnya dengan menggunakan Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). Daripada sejumlag semua sampel 221 sampel udang yang telah dianalisis, residu kloramfenikol ditemui dalam 183 sampel (82.8%) dari julat 0.001-6.283 ng/ml. Residue kloramfenikol dalam 36 sampel (16.3%) sampel melebih Minimum Required Performance Limit (MRPL) 0.3 ng/ml, piawaian keselamatan yang telah ditentukan oleh Kesatuan Eropah (EU). Kajian ini menunjukkan bahawa kloramfenikol mungkin masih digunakan dalam industri ternakan udang di Sarawak.