The project is focused on phylogenetic analyses of myxosporeans - economically and phylogenetically important group of primitive metazoans infecting fish hosts. The main aim is to create the large dataset, which will consist of sequences of ribosomal (SSU and LSU rDNA) and protein genes (HSP70, MHC-II and EF2). The combined analyses may resolve some nodes which are not well supported in the single SSU rRNA gene analyses. The separate analysis of protein genes will be compared with the analysis of ribosomal genes. New sequences and more data could contribute to a better understanding of the relationships of individual myxosporean genera.