Data up to 1995 on the survival of 3-yr cohorts of patients with cystic fibrosis (CF) born in the UK in the period 1968-1992 have previously been published. The present study reports survival data up to the end of 2003 together with a 2003 population estimate. All subjects with CF born in the UK in the period 1968-1992 were identified up to 1997 by active enquiry through recognised CF clinics and other hospital consultants. Information from the death certification authorities up to the end of 2003 was added. Death certificates that could not be matched with UK Cystic Fibrosis Survey records were investigated and the data reconciled. The observed survival up to 2003 of CF patients born in 1978 was 55% for males and 49% for females. For 1988 and 1992 the data were 91 and 88%, and 97 and 96%, respectively. The estimated 2003 mid-year CF population was 8,284. The continuing improvement in survival of cystic fibrosis patients in successive cohorts means that the previous prediction of median survival of >50 yrs of age for individuals born in 2000 continues to look realistic, even in the absence of proven effective therapy aimed at correcting the basic cystic fibrosis defect.