Qualitative and quantitative descriptions of the woody flora and soil analyses are provided for six areas of montane semideciduous forest in the upper Rio Grande region, southern Minas Gerais, Brazil. Comparisons are made of the floristic composition of these six areas and 24 other forest areas of southeastern Brazil using ordination by detrended correspondence analysis (DCA) and hierarchical classifications, both agglomerative (upgma) and divisive (twinspan). The variation in community structure of five of the six forest areas was analysed using a two-way table yielded by twinspan. The floristic analyses indicated the strongest link between the forests of the upper Rio Grande region and other montane forest formations of southeastern Brazil as well as secondary links with the gallery forests that extend into the cerrado domain and the submontane semideciduous forests of the Rio Parana basin. Variations in community structure among the five forest areas were apparently associated mainly with riverside effects and soil fertility. © 1994, Trustees of the Royal Botanic Garden Edinburgh. All rights reserved.