Poultry processors commonly place whole parts of broilers in plastic packages and seal them in an atmosphere of 100% carbon dioxide before shipping them to food service and retail customers. This practice extends the shelf life of retail cuts to approximately 12 d under refrigerated conditions. The objective of this study was to determine the antimicrobial efficacy of vinegar for growth inhibition of mesophilic and lactic acid bacterial counts and enhancement of shelf life in CO2-packaged refrigerated chicken thigh samples. Meat quality, sensory differences, and microbial enumeration were evaluated for chicken thighs that were sprayed with 0, 0.5, or 1.0% vinegar. No differences were observed (P > 0.05) among treatments (control vs. 0.5 and 1.0% vinegar-treated chicken thighs) with respect to pH and Commission Internationale d'Eclairage L*a*b*for both chicken skin and the meat tissue. The difference from the control test indicated that trained panelists were not able to detect a difference (P > 0.05) in flavor between the chicken thigh treatments. The mesophilic and Lactobacillus bacterial counts were enumerated after 0, 4, 8, 12, 16, and 20 d of storage. The mesophilic bacterial load for the 1.0% vinegar treatment was less than all other treatments after 8, 12, 16, and 20 d of storage, whereas the 0.5% vinegar treatment had lower bacterial counts at d 12 than both controls and had an approximate shelf life of 16 d. For lactic acid bacteria, the vinegar 1.0% treatment had lower counts than the control treatments at d 12 and 16. The results from the study indicate that a combination of 1.0% vinegar with CO2 packaging can extend the shelf life from 12 to 20 d for chicken retail cuts without negatively affecting the quality and sensory properties of the broiler meat.