This study aims to improve the knowledge of the Icacinaceae species found in Reserva Ducke. It is based on morphological analysis of herbaria collections and literature compilation. Three species which belongs to two genera were recorded: Casimirella rupestris, Pleurisanthes emarginata and P. parviflora. Casimirella rupestris differs from Pleurisanthes by its stems with stellate trichomes and paniculate inflorescence (vs. globrous or puberulent stems and “spigate” inflorescente in Pleurisanthes), while Pleurisanthes species differs from each other by the leaf margin (denticulate in P. emarginata vs. entire in P. parviflora) and leaf apex (rotund in P. emarginata vs. acuminate-unguiculate in P. parviflora). An identification key, descriptions, illustrations, habitat information, phenology, and species distribution are also provided.