A detailed evaluation is presented of the developmental and cardiopulmonary status at one to five years of age in 22 unselected survivors of severe RDS and IPPB, 15 of whom were considered to have BPD. Fifteen patients (68 per cent) were developmentally "indistinguishable from normal," six (27 per cent) were "suspect," and only one patient had definite developmental impairment. Fifteen of the 22 patients (68 per cent) had persistently abnormal thoracic roentgenograms, with varying degrees of interstitial infiltrates and hyperexpansion. The persistence of abnormal roentgenographic findings was significantly related to duration of ambient O2 therapy; an additional relationship to duration of intubation could not be excluded. Of the 16 patients now over two years of age, eight (50 per cent) have persistent right ventricular hypertrophy, 10 (62.5 per cent) have arterial hypoxemia, and 15 (94 per cent) have AaDO2 values breathing 100 per cent O2 of greater than 100 mm. Hg. Considering the severity of the initial RDS, however, it is significant that 20 of the 22 patients (91 per cent) have no apparent residual cardiopulmonary symptomatology.