Аннотация:The phylogenetic relationships of two Mesozoa groups were studied by the comparative analysis
of complete sequences of 18S and 28S rRNA. Two groups of Mesozoa were found to form a statistically supported clade in phylogenetic trees. The results of the analysis placed Mesozoa in the Spiralia group of Lophotrochozoa and showed the tendency of Mesozoa to converge with one of the Annelida groups.