The purpose of this investigation was to measure the level of bacterial contamination of oysters, and observe antibiotic resistance pattern of Vibro spp. found in oysters. For this experiment, 100 oysters were collected from 100 markets around seoul area from October, 2004 to January, 2005. Bacterial contaminations of the oysters were confirmed by performing the method of standard plate count and desoxycholate lactose agar plate. Total plate counts were $2.7 imes$$10^{2}$$sim$$1.2 imes$$10^{5}$ cfu/g. Coliform group were $1.0 imes$$1.0^{1}$$sim$$3.2 imes$$10^{5}$ cfu/g. Results have shown that Vibrio spp. was present in $64\%$ of the 100 sampls. Antibiotic resistance pattern of Vibrio spp. showed that $MIC_{50}$ of chloramphenicol was 0.2 g/mL, $MIC_{90}$ was 25 $mu$g/mL, and $MIC_{50}$ of tetracycline was < 0.05 $mu$g/mL, $MIC_{90}$ was 25 $mu$g/mL, and $MIC_{50}$ of ciprofloxacin was 0.01 g/mL, $MIC_{90}$ was 10> $mu$g/mL. Three of the six strains were identified as Vibrio alginolyricus.