Madhubani District is the border district of Bihar which is adjacent to Nepal and therefore, bears a rich biodiversity. However, due to rising population, the agricultural lands and forest cover are being converted into residential and industrial land. In addition, over grazing and brutal destruction of the native flora, has caused loss of species in the area. A survey of few Blocks of the district was made in different seasons. Plants were collected and identified with the help of Haines Flora and other books. When the list of the identified species was compared with the species mentioned by Haines in his book, surprisingly it was observed that some of the species are missing in a particular area. Similarly in other areas some species were scattered in such a way that their fecundity was not possible. They were surrounded by another species. Based on the population, density, frequency etc plants were regarded as rare, similarly those species which are mentioned under endangered or vulnerable categories by other workers as mentioned in "Red Data" book were enlisted. KEYWORDS : Biodiversity, Rare, Vulnerable, Endangered, Red Data Book, Fecundity.