Orthosiphon thymiflorus is a medically important plant known for its various pharmacological properties. In the present study the successive extracts of the whole plant of O. thymiflorus was evaluated for their antibacterial property against 11 bacterial strains, of which 10 were clinical isolates and 1 a typed culture. The clinical isolates used for the study were Escherichia coli, Staphylococcus aureus – 2 different strains, Proteus mirabilis, Salmonella typhi, Salmonella paratyphi B, Klebsiella pneumonia, Pseudomonas aeruginosa, methicillin sensitive Staphylococcus aureus and methicillin resistant Staphylococcus aureus from a clinical laboratory and Staphylococcus aureus NCIM 5021 from National Chemical Laboratory, Pune. Well diffusion technique was employed to screen for the activity. MTT assay was used to study the MIC and MBC was also tested. The alcohol extract was found inhibit 7 strains of the 11 strains tested. MRSA was also inhibited. The MIC and MBC was found to range between 0.31mg to 2.9 mg.