The results of long-term studies of meiobenthos from shallow-water gas seeps of Cape Tarkhankut (North-Western Crimea) are presented. It is shown that the meiobenthic communities from the gas seeps are depressed in number in comparison with the surrounding seabed substrates. The density peaks of seep meiofauna are confined to the upper 0-3 cm layer, in contrast to the surrounding sands, where much more abundant meiofauna is located deeper in the sediment layer. Dominant and subdominant meiobenthic taxa are Nematoda, Foraminifera (Allogromiida) and Polychaeta. It is highly likely that a significant percent of the meiofauna that was found in the seep marine sediments are their dead bodies from the surface layers, trapped in the thickness of the microbial mat due to the high rate of growth of the bacterial substrate. Sulphidic seep sediments reduce the concentration of oxygen in the water column at a depth of 1,5 m from the bottom. On the basis of environmental features of the gas seeps, it was described the so-called area of "environmental compromise" as a balance between limiting factors and attractive environment for the benthic biota. Resulting on interaction between limiting and attractive factors, seeps sediments form the specific “extreme” biotopes where rich of nutritious organic matter environment combined with the presence of high concentrations of hydrogen sulfide and lack (or complete absence) of oxygen.