The possibility of measuring thyroid hormones from blood dried on filter paper opened the way to identifying neonates with congenital hypothyroidism (CH) already in the first days of life. Consequently the early initiation of adequate replacement therapy opened the way to an effective prevention of mental retardation. Timely and complete specimen collection, transport logistics, rapid analysis and communication of results are key points for the organization of a CH newborn screening program. Close collaboration between laboratory and treating specialists is necessary to ensure an adequate treatment and follow-up of babies identified by CH screening programs. Topics for further investigations remain in the fields of which forms of CH should be identified by screening (only severe or also very mild forms) and on the long-term outcome of the individuals identified by CH screening.