The efficiency of neonatal screening for CF could be improved by associating a molecular analysis to the immunoreactive trypsin test, on the same dried blood's sample. However the interest of such a screening for the patients benefit remains controversial. In most cases, antenatal diagnosis may be performed by a direct search of the mutation(s). However, the impact of antenatal diagnosis on CF's incidence will necessarily be limited if it can only be implemented after the birth of an affected child. Hence the interest of screening programs for the detection of healthy carriers. Carrier's detection does not raise any objection for the relatives of patients. It is still premature to recommend it to be undertaken in the general population.