The chest radiographs and lung function tests of 41 patients attending the cystic fibrosis clinic at Royal Prince Alfred Hospital were reviewed. The chest radiographs were scored using three different scoring systems: the Shwachman and Kulczycki system (as modified by Doershuk), the National Institute of Health (NIH) system described by Taussig in 1973 and the Brasfield system. The scores were correlated with lung function tests. Significant correlations were found between the radiological scores and the respiratory variables; the best correlation was with the forced expiratory volume in one second (FEV1 % predicted). All three scoring systems showed a high degree of reproducibility of scores when a second radiologist was asked to score the same radiographs independently. The difference in scores between the radiologists was not significant for the NIH and the Brasfield systems. The Brasfield system is, however, the system of choice because it allows the assessment of all the major pathological features seen in cystic fibrotic chest films and consistently has the best agreement with all the lung function variables. It was also found that radiological evidence of lung hyperinflation may not be a good indicator of disease progression.