The present study gives an evaluation of survival in a large italian CF population (536 patients). Sex, meconium ileus at birth, mode of diagnosis (by neonatal screening or by symptoms), were indagated as prognostic factors. Because patients presented with meconium ileus had a worse prognosis (p = 0.0148) than patients normal at birth, survival and prognostic factors analyses were done on 497 patients. The cumulative survival rate (Kaplan-Meier limit product method) (497 patients normal at birth) is 0.96 at the age of 5 years, 0.90 at 10 years, 0.83 at 15 years and 0.74 at the age of 20 years. Statistical analysis was done with BMDP implemented on Unisys 2200/600 on data collected by means of computerized data base (Cystic Fibrosis Data Base-CFDB) which CF Italian Centers are using. Prognostic factors associated with a worse prognosis (Wilcoxon test, Logrank test) resulted: female sex (p = 0.0143), presentation with chronic respiratory symptoms (p = 0.0145), with acute respiratory symptoms (p = 0.0220) and with failure to thrive (p = 0.0007), Chronic pulmonary symptoms and failure to thrive at diagnosis showed the major negative prognostic weight (increased risk of 2.79 and 2.49 respectively) (multivariate analysis by Cox's model).