© 2015 The Association of Anaesthetists of Great Britain and Ireland. Many studies comparing the i-gel™ with laryngeal masks include patients in whom laryngeal mask cuff inflation pressures are higher than recommended, or involve the use of neuromuscular blocking drugs and positive pressure ventilation. We compared the i-gel with the PRO-Breathe® laryngeal mask in anaesthetised, spontaneously breathing children. Two hundred patients aged up to 16 years were randomly allocated to either the i-gel or the PRO-Breathe laryngeal mask. The PRO-Breathe was inflated to an intracuff pressure of 40 cmH2O. All patients received pressure support of 10 cmH2O and positive end-expiratory pressure of 5 cmH2O. Successful insertion at the first attempt was 82% for the i-gel compared with 93% for the PRO-Breathe (p = 0.019). Leakage volume was significantly higher with i-gel sizes 1.5 (p = 0.015), 2 (p = 0.375), 2.5 (p = 0.021) and 3 (p = 0.003) compared with the equivalent-sized PRO-Breathe device. Device dislodgement following successful initial placement was more frequent with the i-gel (5%) compared with the PRO-Breathe laryngeal mask (0%). We conclude that the PRO-Breathe laryngeal mask is superior to the i-gel in terms of leakage volume and device dislodgement.