Multidrug efflux systems are one of the most important antibiotic resistance mechanisms among microorganisms. Efflux pump systems can be specific substrate or can confer resistance to multidrug antimicrobial by facilitating the extrusion of broad rang of compounds including antibiotics, biocides, heavy metals, and organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites. There are few efflux pump inhibitors are available in market and research in progress raises the hope that they may be found in the future.