This report presents the results of a survey of over 800 genetic testing laboratory directors in 18 OECD countries. It provides the first detailed overview of the availability and extent of molecular genetic testing across OECD member countries. The survey allowed the OECD to compare practices in individual countries in order to inform international action in setting standards and developing guidelines for practice. Based on the survey results, the report puts forward recommendations for action for better quality assurance and proficiency of molecular genetic testing. It shows, for example, that requirements for licensing and accreditation/certification of diagnostic molecular genetic testing laboratories have not penetrated OECD countries to a high degree or with any consistency. Considerable variations exist in mechanisms of licensing, certification and accreditation, including the standards by which tests are performed, results are reported, and the qualifications for laboratory personnel.