This work has characterized tree species composition and horizontal structure (HS) of a semideciduous forest plot in the final stretch of the "Espiritu del Bosque" trail, Soberania National Park. For this purpose, we delimited a 1 ha plot, which in turn was subdivided into 10 equal sized subplots (20 x 50 m).  We measured and identified all trees with DBH ? 10 cm and calculated the Importance Value Index (IVI) of tree species to determine HS. On average for each subplot were found 48 individuals and 22 species. A total of 480 individuals were registered, distributed in 78 species, 59 genera and 29 families, being the family Arecaceae (22%) the most abundant, while Fabaceae family with 10 species had the highest wealth. Anacardium excelsum species registered the highest IVI value (18%), indicating that it has a great ecological importance within the studied area.