Significant advances in identifying many different deafness genes have occurred over the last two decades. As a result, genetic testing has become critical for providing personalized therapeutic interventions to patients with hearing loss. However, the number of reported deafness genes is increasing. Currently, 151 genes are thought to be responsible for non-syndromic hearing impairment, with 51 associated with autosomal dominant inheritance (AD), 77 with autosomal recessive inheritance (AR), 6 with X-linked inheritance, and 1 with Y-linked inheritance (Walls et al. Hereditary Hearing Loss Homepage. https://hereditaryhearingloss.org . Accessed 19 Feb 2025). Fifteen genes have been found to be involved in either AD or AR inheritance modes. Depending on the type of variant, either inheritance pattern can occur. Recent discoveries regarding deafness genes have significantly improved our understanding of the molecular mechanisms of hearing. The cochlear and vestibular end organs are made up of various cell types, each of which expresses the genes required for its function and produces the proteins needed for hearing and balance. Pathogenic variants in these genes cause hearing loss due to a lack or alteration in the proteins required for hearing. IHCs and OHCs express a wide range of deafness-related genes, particularly stereocilia-related genes, demonstrating the distinct and important roles of both types of hair cells in sound transduction mechanisms. Supporting cells, such as pillar cells, inner phalangeal cells, border cells, and Deiters’ cells, play important roles in normal hearing function, particularly in the glutamate-glutamine cycle and potassium ion recycling system, which are required for hair cell transduction. Genes expressed on the spiral prominence play an important role in maintaining anion balance. The stria vascularis and spiral ligament express energy-related genes required for effective mechanoelectrical transduction. Furthermore, genes related to the tectorial and basilar membranes are required for adequate amplification of sounds. Normal function requires the coordinated action of these genes, and pathogenic variants that impair gene function cause hearing loss. As so many genes are associated with hearing loss, clinicians are unable to keep track of the causative genes that have been identified. This chapter provides a comprehensive catalogue of the deafness genes reported to date, including their locus, OMIM number, onset age, audiometric configuration, severity of hearing loss, protein function, inner ear localization, and key references.