The study was carried out in the years 2010-2013 on drained, unused meadows situated on organic soils (wet and humid) in central Poland. The paper presents the changes and transformations of habitats and meadow communities that have taken place on these meadows due to reduced anthropopressure. Analysed post-bog meadows were formed by reclamation and drainage of lowland bogs. In the early 90s of the XX century they were still used agriculturally and had valuable meadow communities of the Molinio-Arrhenathereteae class growing on them. As a result of discontinued maintenance of drainage equipment and reduction in pastoral agricultural practices, a large increase in water logging of the post-bog meadows had been observed. This resulted in their conversion into swampy habitats and marshy meadows. Valuable agricultural grasses of the Molinio-Arrhenathereteae class and other humid habitats species receded and the share of herbs and weeds of wet and wetland habitats and/or sedges or Phragmites australis increased. Communities of Scheuchzerio-Caricetea or Phragmitetea classes formed. The problem is still relevant today as similar changes and transformations of plant habitats and communities occur in many valleys.