We analyzed the community structure of an upper montane cloud forest (elevation, 1900 m) in the Serra da Mantiqueira Mountain Range, in the state of Minas Gerais, Brazil. Our objective was to determine the comparative tree species richness and floristic diversity within this forest, which is at one of the higher elevations in the range, in relation to surrounding forests that are at lower elevations, adjusting for elevational gradients. Within 15 permanent plots (40 × 10 m each), we tagged all tree individuals with a diameter at breast height ≥ 5 cm, registering their height and diameter. To compare the study area with neighboring cloud forests, we used the Sorensen similarity coefficient and phytosociological parameters. We sampled 1250 individuals distributed among 89 species, 55 genera, and 34 families. Canonical correspondence analysis revealed no gradients related to the vegetation or soil. We found that tree species richness and diversity were high in the study area. There was structural and floristic heterogeneity among the communities evaluated, underscoring the importance of conservation of these high-elevation ecosystems, which are so unique and irreplaceable.