Ninety-four patients with acquired tracheobronchomalacia were followed up between 1967-1977, for an average of 5.2 years. Fifty-six were still alive at the end of the period, and 47 of these were reexamined. Twenty-one patients had retired on pensions for lung disease. Of the 36 patients who underwent rebronchoscopy, tracheomalacia alone was seen in 3 and tracheobrochomalacia in 33. Six out of the 9 cases of tracheomalacia and all the 5 cases of bronchomalacia had developed into tracheobronchomalacia. The malacia was mild in 6 (17%), moderate in 8 (22%) and severe in 22 (61%), against the figures of the preceding bronchoscopy: 13 (36%), 17 (47%) and 6 (17%), respectively. Mild bronchitic changes were seen in 9 (25%) and severe in 22 (61%) bacterial cultures grew Haemophilus, Proteus mirabilis and Klebsiella, and the culture was positive on 8 occasions (22%). A fungal culture of the bronchial aspirate was positive in 9 cases (25%). No pronounced eosinophilia on the bronchial mucosa was observed.