We report survival data for Danish center-treated cystic fibrosis (CF) patients, covering the period 1974-1993 and using cross-sectional cumulative survival probability based on annual age-specific mortality rates. Analyses by age and by years after diagnosis were made. No significant differences were noted in the survival probability when patients were grouped according to sex or absence/presence of meconium ileus. The annual mortality rate for 1989-1993 was 0-1.2%. Using the age-specific mortality rate for 1989-1993, we were unable to calculate the median survival probability because the curve did not fall below 50% (age up to 45 years); however, it was possible to show that the survival probability for a newborn CF child to reach his 45th birthday was 80.4%(confidence interval 76.5-84.6%). The median age at diagnosis was 0.63 years with no sex difference. The probability of surviving 40 years after the diagnosis of CF was made was 83.3% (confidence interval 80.1-86.6%). This is considerably higher than any other published survival probability. An early anti-Pseudomonas aeruginosa treatment regimen seemed important in achieving the observed improved survival.