The vegetation history of S.W. Connemara was reconstructed on the basis of the available palynological and palaeobotanical data of the region. In the Pre- Boreal Period birch forests replaced the late-glacial tundra-like vegetation. In the early Boreal Period hazel immigrated and the eutraphent water plant communities reached their optimum. After that thermophilous deciduous forests gradually crowded out the birch woods and reached their optimum in the Atlantic Period. The lakes were increasingly filled with peat, the eutraphent character of the marsh vegetation weakened and ombrogenous bog communities spread across the region. Shortly before the Sub-Boreal Period the first indications of human interference in the forests were detectable. During the Sub-Boreal and Sub-Atlantic Periods the forest area was reduced gradually as a result of human activities and the spreading of the bogs. A more or less complete forest clearance took place in the last thousand years.