The aim of this study was to characterize the demographic structure and spatial pattern of Campomanesia xanthocarpa (Mart.) O. Berg, Myrcianthes gigantea (D. Legrand) D. Legrand and Myrciaria delicatula (DC.) O. Berg. Within one hectare of Ombrophilous Mixed Forest, all the three populations' individuals were counted and measured with regard to their height and diameter. From the collected data, the assessment of the demographic structure was realized after the individual's size classification. Spatial pattern was determined by applying the Standardized Morisita's Index. C. xanthocarpa and M. delicatula showed an inverted-J frequency distribution in the individuals size classes, which differed from M. gigantea that did not follow the same pattern. The spatial pattern of C. xanthocarpa and M. delicatula populations was found mainly to be aggregated; whereas, M. gigantea showed spatial randomness. The three Myrtaceae populations responded differently with regard to structure and spatial distribution in sites with the same environmental filters.