The objective of this study was to compare pulmonary function tests of children with bronchopulmonary dysplasia (BPD) and asthma, and to evaluate children with BPD for evidence of upper airway obstruction. This is a case-control retrospective study of pulmonary function tests (PFTs) of 11 children with BPD between 5 and 8 years of age who were followed by pediatric pulmonologists, and of 32 age- and height-matched children with asthma. The median forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF) were significantly lower in the BPD group (0.86 L, 0.79 L, 120 L/min) than in the asthmatic group (1.34 L, 1.21 L, 155 L/min; P = 0.002, P = 0.007, P = 0.004, respectively). Both groups were equally hyperinflated (median thoracic gas volume 155% of predicted values in the BPD compared to 152% predicted in the asthma group; P = 0.67), and both groups showed decreases in air-trapping after a bronchodilator. The ratios of forced expiratory flow at 50% of the FVC to forced inspiratory flow at 50% of the FVC (FEF50%/FIF50%) and FEV1 to PEF (FEV1/PEF) were used to assess upper airway obstruction and were higher in children with BPD than asthma (P = 0.0001 and P = 0.035, respectively). We conclude that pulmonary function of children with BPD who are still symptomatic after 5 years of age is different from age-matched children with asthma, and the children with BPD demonstrate significant inspiratory flow limitations.