Background:Plant-derived compounds have action alongside Gram-positive and Gram-negative bacteria and numerous compounds, inhibit efflux pumps and hence have become known as efflux pump inhibitors. Clarithromycin is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis and acute bacterial exacerbation of chronic bronchitis the antibacterial range is the similar as erythromycin but it is active against Mycobacterium avium complex, M.leprae and atypical mycobacteria. The in vitro antibacterial activity results of different boswellic acid compounds discovered alpha keto-boswellic acid (AKBA) to be the preponderance potent antibacterial compound alongside Gram-positive pathogens, but it showed no significant antibacterial activity (MIC >128 μg/ml) against the Gram negative bacteria. Aim: The aim of present study, is to illustrate the effectiveness of Boswellia carteri against Gram positive and negative bacteria alone and in combination with clarithromycine to elucidate the synergestic antibacterial effects and how Boswellia carteri modifying the antibacterial activity of clarithromycine. Material and methods: The bacteria strains used in this study included five Gram-positive bacteria (Staphylococcus aureus, Streptococcus faecalis, Bacillus cereus, Staphylococcus epidermidis, Staphylococcus saprophyticus) and three Gram-negative bacteria (Klebsiella pneumoniae and Escherichia coli and Pseudomonas aeruginosa) five for each strains. Antibacterial activities were evaluated by measuring inhibition zone diameters by Agar-well diffusion,while Broth dilution method determine MIC.