Background: The nasal valve is the narrowest portion of the nasal cavity and contributes approximately half of the resistance to air flow during breathing at rest. A number of products have been developed to maximise the width of the nasal valve in order to reduce airway resistance and have subsequently beenmarketed to athletes as ergogenic aids. While there is evidence to suggest these products may reduce airway resistance and delay the switch fromnasal to oronasal breathing, themajority of studies have found little improvement in performance. Recently, a new nasal dilator has been released onto the market. This product is unique in that it inserts into the nose and a ratchet system is used to mechanically broaden nasal valve diameter. Therefore, the purpose of this study was to determine if the new nasal dilator improved either submaximal or time trial cycling performance. Methods: Sevenmale cyclists (mean± SD; age 39±14 y, height 183±4 cm, mass 80.8±8.2 kg, VO2peak 4.22±0.39 Lmin−1, Wmax 333±62W), with no ventilatory restrictions, completed two trials onanelectromagneticallybrakedergometer, eitherwithorwithout the nasal dilator, using a randomised, cross-over design. Each trial consisted of a 30min submaximal (50% Wmax) ride immediately followed by a 30min time trial. Oxygen consumption, heart rate, lactate, ventilation (VE, VT, fB), ratings of perceived exertion and performance measures (power output, cadence) were monitored throughout each trial. Results: Three of the seven participants (43%) reported breathing felt easier while wearing the nasal dilator and none of the participants reported any perceived detriment to their breathing. However, there was no difference in any of the physiological, psychological and performance variables measured between conditions during either the submaximal or time trial portions of the test. Discussion: The nasal dilator did not enhance performance or reduce the physiological strain associatedwith the current exercise protocol inmoderately trainedcyclists. Thesedata are in agreement with those previously reported for other commercially available nasal dilators. While high intensity exercise was not improved by wearing the nasal dilator, we did not determinewhether it reduced airway resistance or delayed the switch from nasal to oronasal breathing. Such outcomes might be advantageous in individuals who participate in sports where oral breathing is restricted by protective equipment (e.g. mouthguards, helmet straps) or in clinical populations (e.g., exercise-induced asthma).