Natural and artificial ion transporters consisting of transmembrane channels or carriers are well known. Most of the synthetic transporters concern cation transport, whereas less interest has been shown in anion transport so far. In previous work (Koulov et al. 2003), we demonstrated that a family of small molecules derived from cholic acid termed ‘cholapods’ bind anions with high-affinity, promote Cl- efflux from liposomes and ion transport across polarised MDCK epithelia (Koulov et al. 2003). Using excised inside-out membrane patches from giant liposomes, we compared the activity of cholapods with that of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel under the same conditions. Addition of cholapods caused a concentration-dependent increase in Cl- current, but no unitary events were observed. We present here results obtained with a series of cholapods studied in planar lipid membranes (PLM). Membranes were formed by painting a mixture of POPE/Cholesterol (7/3) plus a known amount of cholapod. Using PLM, we have access to both sides of the membrane and thus to modify its environment. Thus, it has been possible to measure cholapod-mediated current under a series of conditions. Addition of cholapods in DMSO to the cis side of the membrane increased the observed current at an applied voltage (e.g. -100 mV). As the ion concentration was elevated the magnitude of cholapod-induced current saturated. Permeability experiments have been carried out and the transporters show good anion vs. cation selectivity, and also selectivity between anions. We interpret these data to suggest that cholapods can mediate anion transport across artificial lipid membranes by a carrier mechanism. Access to both sides of the membrane makes the PLM a potent technique to analyse the mechanism of action of synthetic anion transporters.