Rapid advances in genetic technology have resulted in the availability of genetic testing as an option for individuals and their families with deafness and hearing loss (D/HL). Recent studies estimate that over 50% of non-syndromic deafness is due to genetic factors with mutations in GJB2, the gene for Connexin 26, causing approximately 30% of cases of sporadic hearing loss and over 50% of cases of congenital severe-to-profound deafness in which there is an affected sibling. It is anticipated that genetic testing will provide a number of advantages by facilitating diagnosis and ultimately impacting prevention and intervention. However, genetic testing is different from most medical tests in that test results are not always 'black and white' (i.e., normal or abnormal) and for many families, genetic concepts of probability and risk are difficult to grasp. Social, ethical and legal issues such as genetic discrimination also are integral aspects of genetic testing. The purpose of this paper is to review the clinical process of genetic testing including genetic counselling for deaf and hard of hearing patients and their families. We highlight the benefits and limitations of testing and provide an overview of the roles of genetics professionals (medical geneticists and genetic counsellors) and health professionals in otolaryngology and audiology.