OBJECTIVE: Oxygen saturation is an important parameter for the follow-up of Chronic Obstructive Pulmonary Disease (COPD) patients. Pulse oximeters are the most common non-invasive way to assess peripheral blood saturation. Invasive way for this is blood gas analyses. Smart watches are actually developed as sports and physical activity watches in order to be used in daily routine by assessing vital parameters such as heart rate, blood pressure and oxygen saturation. In this sense, they can help better monitoring for patients with COPD on the other hand accuracy of these devices is the major concern. BACKGROUND: This study aims to evaluate the correlation of oxygen saturation assessed by smart watch, pulse oximetry and blood gas analyses in COPD patients. METHODS: This is a cross-sectional study evaluating the pulse oximetry technology of smart watch by comparing it real time oxygen saturation measurements of conventional pulse device and arterial blood gas (ABG) analysis in 100 patients with COPD. RESULTS: A moderate correlation was found between oxygen saturation levels obtained by smart watch, pulse oximetry and ABG. CONCLUSION: Smart watches are really smart. Thus, COPD patients can use smart watches to measure oxygen saturation levels in their daily lives. However, SpO2 measurements should be tested in other patient groups and also different degrees of COPD.