Correct determination of absolute values and polarities of liquid junction potentials (LJPs) is essential in patch clamp experiments for the estimation of ionic selectivities and activation voltages of ion channels. A simple approach for the correction of membrane voltages for LJPs has been developed. The method covers all combinations of LJPs between the solutions of bath, patch pipette and reference salt bridge and is applicable to all patch configurations on plasma membranes and endomembranes.