The cochlea is tonotopically organised to ensure that the auditory nerve fibres can be frequency coded in an orderly manner. In part the mechanism depends on the structural and mechanical organisation of the cochlea but it also requires that the individual cells have an organised expression of ionic channels in the basolateral membrane. This short review will discuss evidence for several distributions of K+ and other channels along the cochlea in both mammalian and non-mammalian hearing organs. It will also describe how the gradients are set up and address the question of whether OHCs contribute uniformly to mammalian cochlear tuning.