This research utilization paper reviews the body of published literature on the practice of normal saline instillation before endotracheal suctioning of mechanically ventilated adult patients. Although normal saline instillation before suctioning is a common clinical practice, the research literature does not demonstrate any physiologic benefit to this procedure. Moreover, normal saline instillation may decrease oxygen saturation values (via pulse oximetry) after suctioning. The relevant research studies have been inconsistent and inconclusive because of limitations in sample size and research methodology. Further research studies using larger, more diverse samples, adhering strictly to recommended guidelines for endotracheal suctioning, and examining additional physiologic parameters of oxygenation are necessary. In addition, long-term outcomes of normal saline instillation such as respiratory infection and complications, as well as atelectasis, should be evaluated. Until scientific data can be presented to support the physiologic benefit of this practice, normal saline instillation should be discontinued as a routine or standard practice.