This study was conducted at the laboratories of Food Science Department at the Faculty of Agriculture, Damascus University in order to study the possibility of prolonging the shelf life of chicken breast by vacuum packaging and treating with acetic acid. Chicken breasts were immersed into a solution having 1% or 2% of acetic acid concentration for 30 sec. and packaged with vacuumed and not vacuumed sacs. Samples were preserved at 4±1 ºC for 21 days and examined after 0, 7, 14 and 21 days of refrigeration for microbiological, chemical and sensory properties. Microbiological analyses included determination of total count of bacteria, coliforms, Salmonella, anaerobic bacteria, Pseudomonas, yeasts and molds. Chemical analyses included determination of pH value and non-protein nitrogen. Sensory properties were evaluated for color, smell and texture. Results revealed that samples immersed into a solution with 1% and 2% of acetic acid concentration had affectively improved quality and sensory properties of chicken breast for more than 14 days compared with control samples and the samples treated by 2% of acetic acid with vacuum packaging had the best quality results.