Background: EBUS-TBNA is a frequently used diagnostic method for mediastinal/hilar lymphadenopathies and masses. This procedure is performed with intravenous sedation (IVS). During IVS, patients often develop hypoxemia and nasal oxygen delivery is insufficient in some patients. The aim of this study was to investigate the effect of oxygen application with nCPAP on hypoxemia during EBUS-TBNA. Methods: Patients with EBUS-TBNA indication who did not have any serious heart-lung disease were randomly divided into two groups. One group received only oxygen and the other group received nCPAP+oxygen. Patient characteristics, arterial oxygen saturations, anesthetic agents, CPAP pressures, oxygen concentrations and processing times were recorded during the procedure. Practitioner satisfaction was evaluated at the end. Results: 29 nCPAP+oxygen, 31 oxygen patients were included in the study. There were no significant differences in terms of age, sex, smoking history and presence of additional diseases in two groups. Neck circumference, BMI and STOP BANG questionnaire values were similar. Desaturation time was significantly longer in oxygen group than nCPAP+oxygen group (316±390 sec, 12±118 sec, respectively, p=0,019). Snoring was detected during the procedure in 22 patients in the oxygen group and in 11 patients in the nCPAP group (p=0,01). There were no serious complications in both groups. Practitioner satisfaction was higher in the nCPAP group but this was not statistically significant (p=0,052). Conclusions: Oxygen application by nCPAP during EBUS-TBNA under IVS, significantly reduces desaturation time. Oxygen delivery with nCPAP seems to be a better choice especially for the patients with high Mallampati index.