The objective of the research performed was to evaluate the usefulness of the following parameters: contents of lactic acid and glycogen, pH₄₅, and electrical conductivity (EC2) in Longissimus Lumborum muscle (LL) to evaluate the quality of pork. The above named parameters were determined 45 min post mortem, and, additionally, the electrical conductivity was measured 2, 3 i 24 h after slaughter. It was proved that the determination of the content of lactic acid and EC2 in the LL muscle was more useful for the pork quality evaluation. This is confirmed by the statistically significant correlations among those parameters and the majority of physical-chemical properties of the LL muscle. The statistically significant negative correlation (p ≤ 0.01) between the content of lactic acid determined 45 min post mortem and the pH₄₅ value of the LL muscle (r = -0.72**) suggests the usefulness of those parameters in evaluating the pork quality. The increase (45 min post mortem) in the lactic acid content by 10 µmol/1 g of the muscle tissue contributes to the decrease in pH₄₅ of the LL muscle by as much as 0.1 unit.