As a result of the studies accomplished during about 30 years the diversity of terrestrial vertebrate communities from the RAMSAR humid zone of the Lower Prut was established as well as their proportion (%) in the republic fauna. The abundance of the faunistic diversity is defined by the existence of a complex of different ecosystem types, by the way of bird migration and by the Danube Delta. About 63% of species from the whole terrestrial vertebrate fauna of the republic appear in the zone for reproduction, migration and food. Among these 32 species (mammals-5, birds-24, reptiles-2, amphibians-1) are registered in the Red Book of Moldova. The limiting factors of faunistic diversity abundance are described.