Methods: We conducted a randomized, placebo-controlled, double-blind pilot study to determine whether nebulized recombinant human dornase alpha (Pulmozyme, Genentech) improves radiologic and clinical outcomes in ventilated patients with lobar atelectasis. Outcomes of interest were chest radiograph score, oxygenation, lung compliance, and rate of extubation over the first 5 days. The groups consisted of 14 intervention patients and 16 control patients. They were similar with respect to basic demographics, age, gender, and use of therapeutic modalities relating to lung function. Baseline average chest x-ray scores, Pa02/FI02 ratios, and static compliance were not significantly different. Analysis was limited to the first 5 days.