Use of plant based drugs and chemicals for curing various ailments and personal adornment is as old as human civilization. Plants and plant-based medicaments are the basis of many of the modern pharmaceuticals we use today for our various ailments. The aim of the study was to evaluate the antimicrobial activity of Barringtonia acutangula (Family: Lecythidaceae) and Premna corymbosa (Family: Verbenaceae), two widely distributed shrubs of the Sundarbans mangrove forest by disc diffusion assay. The in vitro antimicrobial activity was tested against E. coli, S. flexneri, S. dysenteriae, V. cholerae , S. paratyphi, Proteus spp, S. aureus and S. epidermis using disc diffusion assay where the chloroformic extract of bark of B. acutangula showed excellent performance against E. coli and the zone of inhibition was recorded as 10mm and 13mm for 500µg and 1000µg consistently. The chloroformic extracts of bark of P. corymbosa also showed significant activity against V. cholera, S. dysenteriae and E. coli respectively. In this investigation Kanamycin (30 µg / disc) standard disc were used as the reference.