Sesbania grandiflora Linn. (Family: Fabaceae) is one of the plants widely used in traditional medicine for the treatment of fever, cough and colds, diarrhea, skin infections and as a skin cleanser. The present study formulated the stem and bark extract of S. grandiflora into an ointment (5%, 15%, 30%) and the antimicrobial activities of each concentration were evaluated by determination of the diameter of the zone of inhibition against Stapylococcus aureus and Staphylococcus epidermidis using disc diffusion method. The study also investigated the chemical constituents of the plant. Preliminary phytochemical evaluation revealed the presence of carbohydrates, flavonoids, phytosterol and phenolic compounds. As per the antimicrobial investigations, the formulated ointment of Sesbania grandiflora ehhibited its highest antimicrobial activity at the concetration of 30% and lowest at 15%.