Recent advances in the molecular biology of hearing and deafness are being transferred from the research laboratory to the clinical arena. This transfer of knowledge will enhance patient care by making the diagnosis of hereditary deafness easier; however physicians and audiologists must clearly identify that subset of the deaf and hearing populations best served by this knowledge. It is also essential for physicians and audiologists to understand the limitations of genetic testing for deafness, and it is imperative that these limitations be appropriately explained to patients and their families. Learning outcomes: The reader will be introduced to the concept of genetic testing for deafness. Two genes that make appreciable contributions to the autosomal recessive non-syndromic deafness (ARNSD) genetic load will be reviewed, GJB2 and SLC26A4. In addition, the unique aspects of genetic counseling for deafness and recurrence chance estimates are explained. © 2002 Elsevier Science Inc. All rights reserved.