This study describes the tree vegetation and soils occurring in a seasonally dry tropical forest (SDTF) and mesotrophic cerradão transition in southwestern Brazil. All trees ≥ 5 cm diameter were measured in 20 plots of 20 × 25 m, 10 in SDTF, and 10 in mesotrophic cerradão. Ten soil samples of 0-20 cm depth were made per plot and mixed in plot groups to produce two composite samples. A total of 71 species was recorded. Anadenanthera colubrina had the highest importance values in both formations. Differences in soil fertility were found between SDTFs (eutrophic soils) and mesotrophic cerradão (mesotrophic soils). A non-metric multidimensional scaling and cluster analysis confirmed the soil fertility segregation, and also showed an agreement between soil fertility and variance in species composition gradients. The mesotrophic cerradão showed higher species richness since it also includes many species typical of more dystrophic and open forms of Cerrado. © 2013 Trustees of the Royal Botanic Garden Edinburgh.