Cystic fibrosis (CF) is a recessively inherited disorder for which screening has been proposed. A number of different screening strategies have been suggested, including prenatal, preconceptional, school and neonatal carrier screening, as well as screening of newborns to identify affected infants. We discuss the advantages and disadvantages of these strategies, and identify gaps in knowledge relevant to decisions to introduce a screening programme for cystic fibrosis. Screening to identify carriers during the newborn period or among school age children is inadvisable, mainly on psychosocial and cost-effectiveness grounds. Although early diagnosis of CF may improve prognosis, current scientific evidence is not sufficient to support screening newborns to identify affected infants. of the remaining two options, prenatal screening has a practical advantage because of existing facilities, while with screening before conception all reproductive options are, in principle, open to detected carrier couples. If adequate pre- and post-test counselling can be provided, both two types of screening could be introduced.