Tumour genetic testing identifies the unique combination of somatic mutations within a cancer clone. This tumour profiling provides clinicians with knowledge about the metabolic and molecular pathways to target when making treatment decisions, improving the care of individual patients. Germline genetic testing, on the other hand, can improve the clinical care of not only the individual cancer patient but also their genetic relatives. This talk will focus on the utility of germline genetic testing for patients and their families (why to test), how to effectively target testing to the patients who are most likely to benefit from testing (who to test), gene panel selection (what to test) and the key discussion points when obtaining informed consent (how to test).