Objective: In our study, we aimed to evaluate the usability of venous blood gas (VBG) in substitution for arterial blood gas (ABG). Methods: In this study, 110 patients with respiratory complaints, who were brought intubated were evaluated prospectively. Arterial and venous blood gases were taken simultaneously shortly before the initiation of oxygen therapy in the emergency department. PH, pO2, pCO2, SaO2, HCO3, lactate (Lac) and BEecf values were recorded. Results: Of the 110 patients included in the study, 75 were male (68.2%), 35 were female (31.8%), and they had a mean age of 53.7 ± 23.1 years. A strong positive correlation between PH, PCO2, HCO3-, BEecf, Lac values (p=0.001) and positive correlation between PO2 and SaO2 values (p= 0.002) were detected. Conclusion: We can conclude that venous blood gas be used in substitution for arterial blood gas in patients who are presented to emergency service and it may reduce the need for arterial blood gas sampling.