After an experimental neonatal screening program for cystic fibrosis (CF) from 1973-1979, a follow-up study took place from 1980-1997. Patients were treated at specialized centres (C) or at local hospitals (non-C). Aims of the study were: 1) to determine whether the previously reported benefits from screening persisted with time and after adjustment for confounding variables; and 2) to investigate whether centre treatment was associated with improved prognosis of CF patients. Prognosis of patients detected by screening (S; n=24) was compared with patients detected clinically, born during (non-S; n=29) and after the screening programme (post-S; n=39). In addition, prognosis was compared between 45 C and 47 non-C patients. Multivariable regression analysis was used to compare survival and mixed-effects model regression analysis was used to compare clinical outcome between patients. The analyses included the variables screening, centre treatment, sex, meconium ileus and genotype. S patients had a significantly smaller decline in forced expiratory volume in one second (FEVI) (difference +2.74% predicted) and significantly lower immunoglobulin-G (IgG) levels (difference -473.69 mg x dL(-1)) than non-S patients until 12 yrs of age. At 12 yrs of age, vital capacity was significantly higher in S patients than in non-S patients (difference +362.79 mL). Survival seemed to be best for S patients compared to both non-S and post-S patients. Post-S patients were significantly heavier (difference in SD weight +0.77), had a significantly smaller decline in FEV1 (difference +2.80% pred) and lower IgG levels (difference -453.04 mg x dL(-1)) than non-S patients until 12 yrs of age. C patients had a significantly improved survival (relative risk (RR) 0.18, 95% confidence interval 0.05-0.57) than non-C patients. Early diagnosis through neonatal screening leads to better preservation of lung function in the long term in cystic fibrosis patients. Management of cystic fibrosis patients in specialized centres improves survival.