The first GRC on Multi-Drug Efflux Systems was held in 2003. This second GRC will focus on how microbes and cancer cells are using membrane-bound efflux pumps with ATP hydrolysis (primary/ABC transporters) or proton gradient (secondary transporters/MFS and others) as the energy source to actively export antimicrobial or anticancer agents from the target microbe or transformed cell. The microbes covered include bacteria, yeast and parasites. The contribution of MDR efflux pumps to intrinsic and acquired resistance to antimicrobials or anticancer agents and subsequent clinical failure is increasingly recognised. Understanding their structure, mode of drug recognition and export, and genetic regulation including gene overexpression and polymorphism is crucial for understanding how microbes and cancer cells develop multi-drug resistance, and for designing strategies to overcome these increasingly-common clinical problems. The first GRC brought together speakers who have had major influence in the field. In addition to overviews by recognized leaders, this second GRC will include state-of-the-art presentations from more junior researchers. Accordingly, this conference will concern itself with the science underlying how cancer treatments can be impacted by drug efflux, and how drug efflux may affect resistance to antibacterials, anti-fungals and anti-parasitic agents. At the first GRC, it became clear to the discrete groups of researchers pursuing investigation on multidrug efflux of anti-bacterial and anti-cancer agents that there were significant overlaps in evolutionary and mechanistic relationships. It is therefore anticipated that this second conference will contribute significantly to the dissemination of the latest information regarding mechanisms of drug resistance. This knowledge should promote the development of novel inhibitors or strategies that could counteract the contribution of efflux to drug resistance.