Investigation of protein changes as well as authentication of meat is particularly difficult in processed meat products due to their different composition, complexity and very often inhomogeneity. The aim of this study was to check if the inter-species differences in the expression of myosin light chain (MLC) isoforms observed in raw meat were retained in meat products. MLCs from mixtures of minced meat (16 variants), frankfurters and sausages (15 products) made from cattle, pig, chicken, turkey, duck and goose were analysed by 2DE. Species-specific patterns of MLC isoforms were observed in all the mixtures and processed meat products. Relatively small degradation was observed in the MLCs after processing. Image analysis enabled species identification of the meat in all samples when the content of meat of one species was not lower than 10%. However, it was impossible to differentiate between all the six species under investigation on the basis of individual isoform. It was possible when the combination of all the three isoforms (myosin light chain 1 fast, myosin light chain 2 fast and myosin light chain 3 fast) was analysed. The results evidenced that MLCs have potential to be used as markers in authentication of meat products made from the analysed six species.