Mongolia is one of the most interesting research areas for botanical systematists and biogeographers because of the country’s geographical location in a depth of the Euro-Asian continent that, according to the world phytogeographical classifi cation by Takhtajan (1978), spans over the Altai-Sayan province belonging to Circumboreal region in the north and northwest, the Manchurian province belonging to Eastern Asiatic region in the east of Boreal subkingdom, the Dzungaro-TienShan and Mongolian provinces belonging Iran-Turanian region in the south-west and south of Tethyan subkingdom of Holarctic kingdom. Although the fi rst attempt to explore the fl ora of Mongolia is credited to D. G. Messerschmidt, who collected the fi rst herbariums from north-eastern Mongolia (valleys of Ulz and Onon rivers), the fi rst inventory list of vascular plants of Mongolia including 489 species was put together by K. I. Maximovicz in 1859. These researchers were followed by dozens of researchers, mostly from Russia, Poland, Germany and other countries. Meanwhile, the conformity of Mongolian territory with the phytogeographical classifi cation by V. L. Komarov in 1908 and of the world by Takhtajan (1978) were revised and there are several works on this issue (Ulziikhutag, 1989). According to the latest classifi cation by Grubov and Yunatov (1952), Mongolia is divided into sixteen phytogeographical regions based on fl oral composition, vegetation and geographical characteristics. A detailed historical review of these research efforts could be found in the works by Ulziikhutag (1989), Hilbig (1995) and Gubanov (1996). Moreover, some families and genera of vascular plants, as well as phytogeographical regions are revised by researchers. For example, a monograph of fl ora and vegetation of East Mongolia was published by Dashnyam (1974) and Dzungarian Gobi and its oasis vegetation was studied by Gal (1975). A list of such studies is enormous and reviewing them will be a challenge. Researches on fl ora and vegetation of Mongolia are still ongoing with higher rate than ever before. Nowadays, there are two publicly accepted major works on the fl ora and plant geographical regions of Mongolia. The Conspectus of Vascular Plants of Mongolia by Gubanov (1996) is the latest that includes all the updates in the fl ora since 1980s. This work appeared after The Keys to the Vascular Plants of Mongolia by Grubov (1982), which is still considered the fi rst major result of studies on fl ora of the country. Here we present a comparison of these two comprehensive works. Our purpose was to determine not only how many species were added to the Mongolian fl ora, but also to differentiate the updated species by taxonomic groups and phytogeographical regions. We believe that such a comparison is important to determine which families and genera or which phytogeographical regions have been most extensively studied between the publication periods of these two major works. We mostly considered the vascular plant diversity of phytogeographical regions in Mongolia in the context of biogeography than separate taxonomic units. The next purpose was to check the similarity between geographical regions by using the latest major work, namely Gubanov (1996), and to estimate an endemism level of each region. Before carrying out analyses, we developed a database of the fl ora of Mongolia which allowed us to perform the comparison. So far, the database only includes data from Grubov (1982) and Gubanov (1996), but we plan to extend it with data from other sources.