Hydromorphic arctic tundra soils are a very important source of atmospheric methane (CH4) which is according to CO2 the most climate relevant greenhouse gas.Wet tundra environments are generally a net carbon sink since the predominant environmental conditions reduce decomposition of organic matter and support a carbon accumulation. More than 14 % of the global terrestrial carbon is stored in soils and sediments of Arctic permafrost environments.Most of the climate models predict a global warming for the next century, which will be shown in deeper and longer thaw processes in the active layer of permafrost soils in the High Arctic and probably of a higher rate of degradation of organic matter and emission of methane and carbon dioxide.The microbial methane production (methanogenesis) is one of the most prominent microbiological processes during the anaerobic decomposition of organic matter. A group of strictly anaerobic organisms called methanogenic archaea is responsible for methanogenesis. The methanogenic archaea use the metabolism end products of bacteria involved in the anaerobic foodchain, which transform complex organic molecules into simple compounds like H2, CO2, acetate, formiate.After its production methane is partly oxidized either in the aerobic top layer of permafrost soils or in the aerobic rhizosphere by highly specialized Proteobacteria, belonging to the group of methanotrophic bacteria. They are using CH4 as the sole carbon source, while energy is gained by the oxidation of CH4 to CO2.In this study the community structure of methanogenic archaea was analyzed by polymerase chain reaction (PCR) using a nested primer approach with two different internal primer sets following denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene fragments. These modern molecular ecological methods allow to study the microbial community including uncultivable microorganisms.To investigate the archaeal community structure samples from three geomorphological different sites were taken:(i) a low centre polygon, (ii) a floodplain (both sites are located on Samoylov Island, Lena Delta) and (iii) a thermoerosion valley (Cape Mammontovy Klyk, ca. 400 km northwest of Samoylov). DNA was extracted directly from soils or from enrichment cultures. Samples for enrichment were taken from two different depths and were incubated under different conditions concerning temperature, salt content and substrates.The comparsion of the three different habitats showed clear differences between the composition of the methanogenic Archaea in the different environments. Both places on Samoylov showed a higher diversity than samples from Mammontovy Klyk. Results also indicate that there is a shift in the community structure from the top to the bottom of the active layer.The DGGE method is a very useful tool to get a fast overview about the composition of microbial communities in complex habitats. It can be also used to controll the enrichment and isolation of pure bacterial cultures.But nevertheless for detailed information about the methanogenic diversity the construction of a clone libary should be the next aim.