This study deals with horizontal product differentiation in the Polish pig meat market. Hypothesis among firms behaviour are derived from an illustrative model and tested in an empirical analysis using data from 1991-1998. The empirical analysis suggest that product differentiation is a relevant phenomenon in the polish pig meat markets. In addition we found that costs and competitions are important factors influencing price variation. However, further influences like price discrimination and vertical product differentiation are also important determinants for product price variations.