Present research was aimed to find out the antibacterial effect of methanolic extract of Oroxylum indicum leaves on E. coli, Klebsiella sp. and Staphylococcus aureus isolates from bovine mastitis samples. Phytochemical analysis of methanolic leaf extract of Oroxylum indicum showed the presence of alkaloids, phenolic compounds, tannins and flavonoids. Methanolic leaf extract of Oroxylum indicum alone when used in disc diffusion test at a concentration of 100mg/ml, did not show any antibacterial activity against E. coli, Klebsiella sp. and Staphylococcus aureus. When the extract was added to antibiotic discs containing Tetracycline, Oxytetracycline and Cephalexin, moderate anti-bacterial potentiating activity was noticed against Klebsiella sp. and potentiating antibacterial activity was observed against Staphylococcus aureus whereas no antibacterial activity was observed against E. coli. From the present study it was concluded that the methanolic leaf extract of Oroxy-lum indicum can be used as a promising antibacterial potentiating agent along with Tetracycline, Oxytetracycline and Cephalexin to treat mastitis caused by Staphylococcus aureus.