This study was carried out to compare the residual antibiotic materials in muscles of slaughter cattle and swine from slaughterhouses in Seoul from 2000 to 2001 by EEC-4-plate method, Charm II and HPLC method. 1. Residual antibiotic materials were detected from 95 samples(0.8%) by EEC-4-plate and 57 samples(10.2%) by Charm II. The final HPLC method determined the positives are 43(45.3%) and 27(47.3%) respectively. 2. The detection ratios were 45% by EEC-4-plate and 47% by Charm II. 3. Seventy samples were classified as tetracyclines 56(75.7.4%), sulfonamides 10(14.9%), $eta$-lactam 6(8.1%) chloramphenicol 1(1.4%). Three of them were confirmed to be positive simmultaneously for tetracyclines, sulfonamides and chloramphenicol. 4. The highest residual concentration of chlortetracycline, oxytetracycline, sulfamethazine, sulfadimethoxine, sulfaquinoxaline, penicillin, ampicillin and chloramphenicol were 0.34, 11.29, 68.16, 0.13, 4.0, 0.12, 0.4 and 0.04ppm, respectively.