This study was conducted to investigate the effects of a no saline, a 2 ml and a 5 ml saline instillation prior to endotracheal suctioning on oxygen saturation in patients with pneumonia. The subjects in this study were 16 pneumonic patients with a tracheotomy tube, who had been admitted to the neuro-surgical intensive care unit at a university hospital in Seoul Korea. All three (0, 2 and 5 ml) saline instillation methods were applied to the 16 patients. The methods were randomly assigned to each patient. Each of the instillation methods was applied in a four-step sequence: 1) recording the level of oxygen saturation (baseline levels), 2) instilling normal saline, 3) supplying oxygen and suctioning, and 4) recording the level of oxygen saturation. The oxygen saturation was evaluated using pulse oximetry. The recovery times for oxygen saturation to return to baseline levels following suctioning were, just after suctioning, 45 seconds after suctioning and in excess of 5 minutes with 0, 2 and 5 ml saline instillations, respectively. Instillation of normal saline before suctioning could have an adverse effect on oxygen saturation, and should be used carefully as a routine intervention in patients who have pneumonia.