Purpose: To provide an overview of the methodologies involved in the field of hair cell regeneration. First, the author provides a tutorial on the biotechnological foundations of this field to assist the reader in the comprehension and interpretation of the research involved in hair cell regeneration. Next, the author presents a review of stem cell and gene therapy and provides a critical appraisal of their application to hair cell regeneration. The methodologies used in these approaches are highlighted. Method: The author conducted a narrative review of the fields of cellular, molecular, and developmental biology, tissue engineering, and stem cell and gene therapy using the PubMed database. Results: The use of biotechnological approaches to the treatment of hearing loss--approaches such as stem cell and gene therapy--has led to new methods of regenerating cochlear hair cells in mammals. Conclusions: Incredible strides have been made in assembling important pieces of the puzzle that comprise hair cell regeneration. However, mammalian hair cell regeneration using stem cell and gene therapy are years--if not decades--away from being clinically feasible. If the goals of the biological approaches are met, these therapies may represent future treatments for hearing loss.