BACKGROUND: Mechanical ventilation requires an endotracheal tube. Airway management includes endotracheal suctioning, a frequent procedure for patients in the ICU. Associated risks of endotracheal suctioning include hypoxia, atelectasis, and infection. There is currently no evidence about the safety of avoiding endotracheal suction. We aimed to assess the safety of avoiding endotracheal suction, including at extubation, in cardiac surgical patients who were mechanically ventilated for^12 h. METHODS: We conducted a single-center, noninferiority, randomized controlled trial in a cardiac ICU in a metropolitan tertiary teaching hospital. Subjects were assigned to either avoidance of endotracheal suction or to usual care including endotracheal suctioning during mechanical ventilation. In total, we screened 468 patients and randomized 249 subjects (usual care, n 5 125; intervention, n 5 124). Subjects were elective cardiac surgical patients anticipated to receive^12 h of mechanical ventilation. The primary outcome was the P aO 2 /F IO 2 on room air 6 h after extubation, with a noninferiority margin of 10% (lower bound of one-sided 95% CI to be < 30). RESULTS: There were no differences in group characteristics at baseline. The primary analysis was a per-protocol analysis performed on 154 subjects. The median P aO 2 /F IO 2 was 323 for the intervention group and 311 for the standard care group (median difference 5 12, one-sided 95% CI-14.3). The results were consistent when using an intention-to-treat analysis and a 97.5% CI. There were no differences between groups in complications or safety measures, including the escalation of oxygen therapy. CONCLUSIONS: Endotracheal suctioning can be safely minimized or avoided in low-risk patients who have had cardiac surgery and are expected to be ventilated for < 12 h after surgery.