Genetic diseases are very numerous, even though rare as single conditions: therefore, overall they represent a significant portion of morbidity at population level. The improvement of molecular genetic techniques has brought a great increase in the diagnostic potential toward genetic diseases, concerning either symptomatic or pre-symptomatic individuals and healthy carriers. However, this has frequently unforeseen consequences, such as a discrepancy between diagnostic and therapeutic potentials. Moreover, the development of genetic tests has raised a number of questions regarding ethical, legal e social problems. The Italian guidelines for genetic tests (available on the Internet site of Istituto Superiore di Sanità: http:@www.iss.it) have been elaborated in 1998 to define general principles for performing and managing genetic tests as well as for programming and promoting genetic testing within the public health system. In accordance with recommendations by international bodies (WHO, EU), the Guidelines give emphasis to the appropriate use of both safe and efficacious tests, the performance in laboratories with high quality standards. A further crucial point is the relationship between the health system and individuals: authonomy of decision, psychological and social assistance, as well as adequate attention to ethical and privacy problems should be guaranteed.