The public already has concerns about 'the new genetics', and it is clear that confidence can only be maintained by scrupulous attention to quality. Standards can be improved by harmonization of methods, discouraging poor practice and using appropriate internal and external quality controls. At present, despite the profound implications of genetic test results, few genetic tests are subject to sufficient scrutiny. The Human Genome Project will lead to the identification of numerous genetic variations contributing to multifactorial diseases, and high-throughput technologies will permit the generation of disease-susceptibility profiles. Clinical laboratories will need to develop the wherewithal to handle these data and present them in a format that is clinically useful.