With healthcare objectives and budget constraint, remote monitoring of chronic obstructive pulmonary disease (COPD) patients is an important challenge in most European countries. Recent works have shown that it is possible to predict COPD exacerbation based on monitoring of simple parameters, such as the respiratory rate (RR) of the patient in spontaneous ventilation or under non-invasive ventilation. Until now, these devices do not allow a daily automatic data remote transmission,[4] or it is restricted to patients under mechanical ventilation. TeleOx® (SRETT, Boulogne-Billancourt, France), the first oxygen flow rate remote monitoring device, also allows a RR measurement by associating a pressure sensor and a fluidic oscillator flow sensor. A median RR is output every 5 minutes based on time interval between two consecutive respiratory cycles. In this study, we compared the corresponding RR measurements between TeleOx® and the reference polygraph (Nox-T3®, Nox Medical Inc. Reykjavik, Iceland) from COPD patients under nasal oxygen therapy with flow rates between 0.5 and 5.0 litres per minute. Patients without mechanical ventilation and without any other respiratory pathology were eligible to the study if they would undergo a ventilatory polygraph record for other reasons