The construction of new specific tapeworm primers allowed synthesis of a 311-bp fragment of the mitochondrial 12S rDNA of 11 Taenia species and two Echinococcus species by PCR. After direct sequencing and construction of an alignment, the DNA sequences were calculated by three different phylogenetic algorithms. The phylogenetic trees were tested by 1000 bootstrap replications. Reliability of the nodes was tested by splits testing. All three algorithms revealed a clear monophyletic phylum Taenia, suggesting it may be paraphyletic with respect to the genus Echinococcus. Within the genus Taenia, the first secure group was composed by Taenia saginata, T. solium, T. serialis, T. ovis and T. hydatigena. A delimited second group was formed by T. martis, T. taeniaeformis, T. mustelae and T. parva. All of them were opposed to the genus Echinococcus using other cyclophyllideans as an outgroup. In this study Echinococcus was used as an outgroup, being the closest species against which the ingroup could be routed. The findings of this publication reflect Verster's basic morphologically based grouping of the Taeniidae.