BACKGROUND: Positive expiratory pressure (PEP) is regularly used as a self-administered airway clearance technique. OBJECTIVE: The aim of this study was to evaluate the need to teach the correct use of the PEP device and to measure the progress of the success rate of the maneuver after training. METHOD: A PEP system (PariPEP-S Sytem) was used to generate PEP in 30 healthy volunteers. They were instructed by a qualified physical therapist to breathe correctly through the PEP device. Then they were evaluated during a set of ten expirations. Two other evaluations were performed at day 2 and day 8 (before and after feedback). The mean PEP and the success rate were calculated for each set of expirations. The number of maneuvers needed to obtain a correct use was calculated on the first session. RESULTS: An optimal PEP was reached after 7.5 SD 2.7 attempts by all subjects. Success rates and mean pressures were similar between the different sets of expirations (p=0.720 and p=0.326, respectively). Pressure variability was around 10%. After one week, 30% of subjects generated more than two non-optimal pressures in the set of ten expirations. No difference in success rate was observed depending on the evaluations. CONCLUSION: This study demonstrates that good initial training on the use of the PEP device and regular follow-up are required for the subject to reach optimal expiratory pressure.