Studies on ecological distribution of silver (Betula pendula Roth.) and downy (Betula pubescens Ehrh.) birch in mire (natural and drained) habitats were conducted in 45 birch stands (older than 10 years) and in 25 former clearcut habitats (up to 10 years of age) where no silvicultural measures were applied. The distribution of silver and downy birch in birch stands of different age, growing on mire habitats of different types (trophotop) and in various mire zones, was determined; the influence of different factors (stand age, site hydrotope and trophotope, etc.) on their distribution was estimated. The portion of silver birch in the species composition of raised bogs and transition mires decreases with age. In fens silver birch grows only in young, up to 10-year old, stands. In different mire zones, silver birch is distributed rather unevenly. The depth of ground water level, seed source, litter/peat layer depth produce the strongest influence on silver and downy birch distribution in mire habitats. The influence of grasses and litter/peat layer depth on birch species composition is significant only in the initial period of stand regeneration.