Chest radiographic scores and respiratory function on 80 sets of results from 50 patients with Cystic Fibrosis were analyzed. Chest radiographic scores were assessed independently using the method of Chrispin and Norman. Respiratory function tests were found to correlate well with the chest radiographic score, the best correlation being with the forced expiratory volume in 0.75 sec. to forced vital capacity ratio F.E.V. 0.75/ F.V.C. (r = -0.674 n = 80 p less than 0.001).