OBJECTIVE: To compare the delivery of an albuterol metered-dose inhaler (MDI) (Ventolin) via an Aerochamber (Monaghan) with an inline adapter (Medicomp Straight Swivel) in an in vitro infant lung model. METHODS: An in vitro infant lung model was modified to compare the delivery of albuterol MDI 10 inhalations via an Aerochamber with an inline adapter. The adapter and Aerochamber were placed at the endotracheal tube. A 1000 mL intravenous bag filled with 500 mL deionized water was attached to a 3.5 mm endotracheal tube (10 cm length). An Infant Bear Cub ventilator was used at the following settings: positive inspiratory pressure 20 cm H₂O, intermittent mandatory ventilation 40 breaths/min, positive end expiratory pressure 4 cm H₂O, and inspiratory time 0.5 second. Each device was run at least 10 times and assayed in duplicate by HPLC. An unpaired Student's t-test was used to analyze the statistical significance of the data. RESULTS: There was significantly greater delivery of albuterol with the Aerochamber (19.49 ± 7.23 μg; 2.17% ± 0.8%) as compared with an inline adapter (1.0625 ± 1.36 μg; 0.12% ± 0.15%) (p = 0.001). CONCLUSIONS: The Aerochamber provides a greater delivery of albuterol metered-dose inhalations to the lung than the inline adapter in an in vitro infant lung model.