In Italy, since 2016, extended neonatal screening has been mandatory throughout the country for about 40 inherited metabolic diseases. The law contains indications on: the list of pathologies, the information and consent, the methods of collecting and sending samples, the newborn screening system with the elements of its organization, appointed to guarantee the entire path of newborn screening, from the level I test to taking charge of the confirmed positive newborn, the communication and recall procedures for diagnostic confirmation and patient management, training and information initiatives, as well as the criteria for allocating the allocation. Extended neonatal screening has introduced new issues in diagnosis, choice of decision levels, and metabolic disease panels to screen. Of particular relevance in order to a strong reduction of false positives, was the introduction of the second-tier test for some diseases such as leucinosis, isovaleric acidemia, methylmalonic aciduria. As regards the diseases to be screened, the Italian situation differs greatly from what happens in Europe where in the majority of member states there is no legislation / law governing this preventive pediatric service; screening is almost always on a voluntary basis (with the collection of written informed consent from both parents) and applied on the basis of health guidelines or recommendations. In the world, the most complete panel is the US one (RUSP, Recommended Uniform Screening Panel) which currently contains 62 pathologies, 35 of which are defined as core panels and 27 as secondary panels. As the name implies, it is a panel that the US Health Resources and Services Administration -HRSA- recommends that it be applied by every State and that includes new screening in some areas including Pompe disease and MPS I, creatine deficiency. In conclusion, extended neonatal screening represents a real revolution in the metabolic field offering newborns an early diagnosis combined with effective therapeutic treatments capable of radically changing the course of these serious diseases.