The present study was carried out to investigate Sesbania sesban (L) Merr leaves pharmacognostic and phytochemical, in-vitro and in-vivo antidiabetic screening. Sesbania sesban (L) merr leaves was collected from local and surroundings areas in Karnataka and authenticated by renowned botanist. Authenticated plant material was subjected to morphological and microscopical analysis. Shade dried and powdered leaves was subjected to successive soxhlet extraction with organic solvents of increasing polarity like Pet. ether, chloroform, ethyl acetate and alcohol. All the extracts were evaluated by qualitative chemical examination for the presence of important phytoconstituents and confirmed by TLC studies.One phytoconstituents (COMP-I) were isolated from ethanolic extract by column chromatography and an attempt was made to characterize the isolated compounds by TLC, UV, FT-IR, 1H-NMR, 13C-NMR and Mass spectroscopicstudies. Characterization revealed that COMP-I may be a flavonoid moiety. The in vitro anti-TB studies of Sesbania sesban (L) merr leaves were studied by invitro Micro plate Alamar Blue Assay (MABA) method and results revealed to be equipotent when compared to standard drugs like pyrazinamide, streptomycin and ciprofloxacin.In this study an attempt was made to provide scientific backup to the traditional claim. Since the results showed a significant anti-TB activity the traditional use of Sesbania sesban (L) Merr leaves for the anti-TB activity may be justified.