Little is known of the molecular basis of normal auditory function. In contrast to the visual or olfactory senses, in which reasonable amounts of sensory tissue can be gathered, the auditory system has proven difficult to access through biochemical routes, mainly because such small amounts of tissue are available for analysis. Key molecules, such as the transduction channel, may be present in only a few tens of copies per sensory hair cell, compounding the difficulty. Moreover, fundamental differences in the mechanism of stimulation and, most importantly, the speed of response of audition compared with other senses means that we have no well-understood models to provide good candidate molecules for investigation. For these reasons, a genetic approach is useful for identifying the key components of auditory transduction, as it makes no assumptions about the nature or expression level of molecules essential for hearing. We review here some of the major advances in our understanding of auditory function resulting from the recent rapid progress in identification of genes involved in deafness.