Abstract. ABSTRACTThis study aimed to diagnosis structural variations between floristic groups in a remnant of MontaneMixed Ombrophylous Forest in Nova Prata, RS state. To do so, 71 plots with dimensions of 10 x 100 mwere inventoried, distributed by the process of systematic sampling in Two Stages. All individuals withcircumference at breast height equal to or above 30.0 cm were measured. The cluster analysis based on theabundance of species in each plot was conducted by using Ward connection method and it allowed classifyingthe plots in four distinct floristic groups. Intermediate Stage, Border Forest, Advanced Stage and DegradedForest Groups presentedMatayba elaeagnoidesRadlk,Lithrea brasiliensisMarchand,CampomanesiaxanthocarpaO.Berg andMyrciaria floribundafloribunda(West ex Willd.) O. Berg, respectively, as the mostcharacteristic species. Greater variation in the proportion of understory species and pioneers was found. Thehighest number of species with the aggregated spatial distribution pattern was observed. The diameter andhypsometric structures indicated the groups have a good renewal capacity and a denser bottom canopy, respectively, although they have some different characteristics. In summary, the groups presented structuralvariations that evidenced the need to consider the clusters in the event of intervention in the forest.