The aim of the study was to analyse the effect of CO₂ concentration in pharmacological stunning method of pigs on selected quality traits of meat. Investigations were carried out on 200 fatteners of mass population. Half the animals (n=100) were stunned with 92% and the other 100 fatteners were stunned with 88% CO₂. The stunning effectiveness was evaluated by observing animals’ response to CO₂ concentration. In the group of the fatteners stunned with 92% CO₂, all animals were stunned correctly, whereas in the group of the fatteners stunned with a lower concentration of CO₂ (88%), the percentage of ineffectively stunned animals reached 17%. A statistically significant (p<0.01) influence of carbon dioxide concentration in the pharmacological stunning method was noticed on pH24, lightness of meat – L* (p<0.05) and b* value. A higher frequency of carcasses with PSE and DFD was observed among the fatteners stunned with 92% CO₂ (respectively 16% and 7% vs. 9% and 1% reported for animals stunned with 88% CO₂).