Background. CF carrier screening is a genetic test to identify carriers among reproductive adults, namely the so-called heterozygotes who have one copy of the mutated gene and therefore are not sick, but can transmit the disease to a child if the partner is carrying a similar mutation. Over the past 10-15 years in the western part of the Veneto and Trentino-Alto Adige, the test has been used with caution and offered to those who already had a case of cystic fibrosis in the family. For the past ten years the University of Padua took a different policy and launched a campaign of active offer of CF testing to the general population. As a consequence, in the eastern region thousands of tests have been performed, identifying CF carriers. In the eastern Veneto region, the number of newborns with cystic fibrosis has fallen year after year until almost to zero, while this decrease was lower in the western part of the Veneto and Trentino-Alto Adige.