Newborn screening-an important preventive public health programme, is useful in establishing early diagnosis and timely delivery of medical interventions in newborns with rare diseases. Cystic fibrosis (CF) is the most common autosomal recessive monogenic disease of the Caucasian population, with chronic progressive evolution, potentially fatal characterised by the triad of exocrine pancreatic insufficiency + chronic lung disease + increased levels of chlorine and sodium in sweat. Early detection of CF can result in considerable health benefits. However, inevitably it also always implies negative effects. Wilson and Jungner developed ten criteria for the screening to balance pros and cons. Arguments for newborn screening for CF: 1. According to the first criteria, CF is an important health problem. 2. Newborn screening allows early diagnosis when the child is asymptomatic or has a few symptoms. 3.?Most patients with CF are pancreatic insufficient at birth or develop pancreatic insufficiency during the first year of life. So, with an early diagnosis the child can receive from the start pancreatic enzyme replacement therapy. 4. Early diagnosis and treatment are related to better lung function (better forced expiratory volume, early start of the eradication treatment of the infections with pathogenic microorganisms) and a growth pattern that approximates that of healthy children. 5.?The opportunity that parents receive genetic counselling which is important for family planning. 6. Newborn screening for CF is cost-effective. Arguments against newborn screening for CF: 1. False positive tests often lead to parental stress and anxiety. 2. Posibility to identify the carrier status can also lead to stress, especialy when only one parent is identified as carrier. 3. Infants identified by newborn screening will mostly visit CF clinics at an earlier age, presenting a risk for cross-infections. Conclusions: The benefits of newborn screening for CF are now generally accepted. However, the disadvantages hamper its introduction in routine screening programmes.