Although shown to be safe in many other lung disorders, the safety of fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) in critically ill patients with adult respiratory distress syndrome (ARDS) remains unproven. We conducted a prospective study to evaluate the safety of BAL in patients with ARDS. There were 438 patients with ARDS at our institution during the study period. Of these, 110 underwent FOB and BAL for either research or clinical purposes. Data were collected at baseline, at 5-min intervals during the procedure, and 1 h after the procedure. We did not detect any statistically or clinically significant changes in PaO2/FlO2, mean arterial pressure, heart rate, peak inspiratory pressure, or static thoracic compliance after the procedure. A small decrease in SaO2 occurred after BAL. Although this change was statistically significant, the magnitude was not of clinical importance. Five patients (4.5%) had transient arterial oxygen desaturation to < 90% during FOB and one patient (0.9%) experienced desaturation to < 80%. There were no prolonged episodes of severe hypoxemia. No serious bleeding occurred. One pneumothorax developed during the procedure. No deaths occurred that were related to the procedure. We conclude that FOB and BAL can be performed safely and are reasonably well-tolerated in patients with ARDS.