In this study the influence of gradual increase of carbon dioxide concentration (percentage by volume in air) on Yersinia enterocolitica counts was examined the during packaging and storage of ground pork meat artificially contaminated with these bacteria was evaluated.  Ground meat was packaged under customary conditions using vacuum and modified atmospheres with various carbon dioxide percentages (MAP 1 consist of was 20% O2, 50% CO2 and 30% N2, MAP 2 was 20% O2, 30% CO2 and 50% N2). The packs were storage at 4±1 ºC for 12 days. During the entire storage time, counts of Y. enterocolitica were determined by plate method for direct plate counts. Also, microbiological shelf life of the stored pork meat was assessed by Enterobacteriaceae and total aerobic bacteria plate counts. Y. enterocolitica counts were not significantly different (p>0.01; p>0.05) in the pork under various packaging, but it was significantly different (p>0.01; p>0.05)  between days of comparing in the same packs. Packaging with high CO2 concentration had inhibitory effect on the grown of Y. enterocolitica and Enterobacteriaceae.