The usefulness of a chest radiograph scoring system to predict chronic oxygen dependency (oxygen dependency at 36 weeks post conceptual age) was determined in 40 infants with a median gestational age 27 weeks (range 24-32 weeks). The scoring system assessed the appearance of the preterm infant's chest radiograph taken at one month of age, and graded the radiograph according to lung volume, the presence of opacification, cystic elements and interstitial change (maximum score 24). Infants who were chronically oxygen dependent had significantly higher scores (median 9, range 7-20) than those not oxygen dependent (median 3, range 0-13, P less than 0.01). All nine chronically oxygen dependent infants had a score greater than 6, in comparison with only two of 31 infants not chronically oxygen dependent (P less than 0.01). A chest radiograph score of 6 thus had a sensitivity of 100% and specificity of 93.5% in predicting chronic oxygen dependency.