Resumo. This study aimed at evaluating the fitossociology of Mixed Rainy Forest, departing from the grouping analysis. For that, six conglomerates were used, each one with 16 plots, where the arboreal and shrub individuals with breast height circumference (CAP) equal or larger than 30 cm was identified and measured. The species were classified in ecological groups and, beginning with the density data, a grouping analysis was accomplished using the method TWINSPAN (Two-way Indicator Species Analysis). The groupings were characterized in relation to their horizontal structure. In the area, 86 species were identified, being 18 ioneers, 25 secondaryinitials, 16 secondary late, 14 climax and 13 were classified in more than one group. Three groupings were identified (Groups 1, 2 and 3), where the species Siphoneugena reitzii, Araucaria angustifolia and Sebastiania commersoniana were stood out, respectively, in hillside environment, open and humid forest. It was observed that the individuals¿ presence with smaller diameter will guarantee the permanence of these species for a medium period. It is ended that interventions silviculturais in this ecosystem consider the presence of different groupings, characterized by environment and specific species.