This paper gives an overview of the eight associations of the phytosociological class Bidentetea tripartitae TX. et al. ex VON ROCHOW in the state Mecklenburg-Vorpommern in Northeast Germany. All communities are characterised floristically and ecologically. The class is divided into two alliances. The central alliance Bidention tripartitae comprises five associations, named Polygonetum hydropiperis, Corrigiolo litoralis-Bidentetum radiatae, Rumici maritimi-Ranunculetum scelerati, Alopecuretum aequalis and Bidentetum cernuae. These grow at the margins of standing or streamless bodies of waters such as small pools, fishponds or settling ponds and are typical for wet, often inundated mud soils. The second alliance, Chenopodion rubri, is well characterized by a number of species and contains three associations, Chenopodietum rubri, Xanthio albini-Chenopodietum rubri and Chenopodio polyspermi-Corrigioletum litoralis. These communities grow mainly along the banks of the river Elbe on sandy, gravel substrate. Only the Chenopodietum rubri is found in other regions and on mud soils as well. The syntaxonomic treatment is based on the Braun-Blanquet approach as specified in the classification method of DENGLER & BERG (2002). In comparison with the relevés of all other syntaxa stored in the vegetation data base of Mecklenburg-Vorpommern (BERG et al. 2001 b) it could be shown that some species usually treated as character species of or within the Bidentetea as Bidens tripartita and Persicaria hydropiper do not meet the character species criterion in Mecklenburg-Vorpommern while Oenanthe aquatica (often classified with the reeds) indeed is a regional character taxon of the class Bidentetea. All syntaxa are named according to the ICPN. In addition, the treatment contains the most common synonyms and the reasons for the invalidity or illegitimacy of these, respectively. Nomenclatural types are assigned for seven syntaxa not yet typified. Furthermore, four names of syntaxa are proposed as nomina dubia. Other communities which probably merit association rank but which do not occur in the area of investigation are mentioned. The two alliances show clear differences in their species spectra with regard to sociological groups, life forms and strategy types. Example given the portion of therophytes is higher in the Chenopodion rubri, that of hydrophytes in the Bidention tripartitae. Finally the article provides some information on aspects of biodiversity and nature conservation of Bidentetea communities.