The Himalayan forests are highly threatened due to anthropogenic pressures ranging from agriculture intensification, deforestation, hydropower development, etc. The present study attempts to document the floristic diversity, composition and structure of vegetation communities in the tropical semi-evergreen forest of North Cachar Hills in Assam. A one-time assessment was made during the peak growing season in a 4000 m2 forest area to make an inventory of vegetation structure by using the nested quadrat method. A total of 445 individuals belonging to 52 tree species were recorded from the overstorey, while 161120 individuals belonging to 72 species were recorded from the understorey vegetation. The forest stand structure exhibited a reverse J-shaped population curve, and most tree species showed no regeneration (57%), while others showed either good (23%) or poor (17%) regeneration. This study highlights that the understorey vegetation is as important as the overstorey vegetation with respect to species diversity. This study can serve as a baseline for assessing the impacts of different natural and anthropogenic threats on biodiversity in the study area. Additionally, this study highlights the need to conserve the natural forests of Northeast India and protect them from different threats.