The Ducke Forest Reserve, with an area of 100 km2 and located close to Manaus, is one of the sites with highest density of botanical collections in the INPA herbarium. The reserve's vascular flora (excluding Pterophyta) is described based on a survey of approximately 7,107 specimens, of which 4,946 are determined to species. Though many specimens are sterile, undetermined, or not yet examined by specialists, this sample provides a preliminary floristic description of the reserve. The flora now stands at 1,199 species (or 1,453 if indeterminate are included), representing 510 genera and 112 families. The ten most speciose genera -- with a total of 222 species -- are predominantly arborescent: Pouteria (38 species), Miconia (27), Protium (24), Licania (23), inga (21), Ocotea (20), Swartzia (19), Eschweilera (19), Virola (16) e Sloanea (15). The ten most common (i.e., most collected) species comprise only 8.2% of the pool of determined specimens. These are also tree species: Microplholis guyanensis (A. DC.) Pierre, Chrysophyllum sanguinolentum(Pierre) Baehni, Trattinnickia glaziovii Swart, Goupia glabra Aubl., Scleronema micranthum Ducke, Aniba panurensis (Meissner) Mez, Laetia procera (Poeppig) Eichler, Caryocar villosum (Aublet) Pers., Brosimum rubescensTaubert,Cecropia sciadophylla Mart. Only 123 species (10.3% of the determined species) are considered common, being those with ten or more collections. The majority of the 1,199 determined species are very rare; 68% are represented by three or fewer collections and 43% are represented by a single collection. Therefore, many additional "rare" species will be added with additional collecting of the reserve or with the study of indeterminate material. Discussion and graphs comparing the most speciose and most commonly collected families and genera is included.