During a multicentric pilot screening program for congenital hypothyroidism a comparison between the results obtained from Urbino, an area characterized by low iodine supply and endemic goiter, and Rome, a non-endemic area, has been made. The evaluation of neonatal urinary iodine excretion in the two areas showed significantly lower iodine urinary excretion levels in Urbino than in Rome. A shift of TSH at screening toward higher values as well as a higher percentage of recall in Urbino area than in Rome was observed. This finding, which well correlates with a low environmental iodine supply, emphasizes the importance of screening for congenital hypothyroidism as a suitable index of the presence and action of goitrogenic factors in the environment.