Objective: To evaluate pulmonary function and bronchodilator responses in young children with chronic pulmonary disease (CPD) after a severe adenoviral lower respiratory tract infection. Methods: Pulmonary function tests were performed in 13 patients (mean age, 1.32 ± 0.8 years) with CPD and were compared with a control group of 13 healthy infants (mean age, 1.16 ± 0.4 years). Results: Respiratory rate, peak tidal expiratory flow (PTEF), PTEF/tidal volume, absolute time up to PTEF, time percentage to PTEF, volume percentage for PTEF, and compliance and resistance of the respiratory system were significantly affected in the CPD group. Similarly, maximal flow at functional residual capacity (V ́maxFRC) was 56.0 ± 42 mL/s and 373 ± 107 mL/s in the CPD and control groups, respectively (P = .001). No within-group differences with baseline values or between-group differences were noted in response to treatment with ipratropium bromide or albuterol. Conclusion: Young children with CPD caused by adenovirus have pulmonary function changes characterized by severe obstruction and diminished lung distensibility not responsive to the administration of inhaled ipratropium bromide or albuterol. (J Pediatr 134:730-3)