The i-gelTM and LMA SupremeTM are extraglottic airway devices with non-inflatable and inflatable cuffs, respectively. We hypothesised that directly measured mucosal pressures would differ between these devices in anesthetised paralysed patients. Thirty patients were randomly allocated to receive one of these two devices. Four pressure sensors were attached to all airway devices used to measure mucosal pressure at the base of the tongue, the distal oropharynx, the hypopharynx and the pyriform fossa. At these four places, median (IQR [range]) i-gel mucosal pressures were 8.0 (2.7–10.7 [0–26.7]), 5.0 (2.7–7 [1.0–37.3]), 9.3 (2.7–13.3 [0–22.7] and 8.0 (2.7–10.7 [0–25.3]) cmH2O, respectively, and for the LMA Supreme, these were 5.0 (0.5–8.0 [0–33]), 4.0 (1.3–9.3 [0–24]), 10.7 (4–17.3 [0–26.7]) and 8.0 (0–10.7 [0–36]) cmH2O, respectively. Mucosal pressures were low and similar for both devices. The LMA Supreme mucosal pressures were higher in the hypopharynx than in the distal oropharynx (p = 0.04) and base of the tongue (p = 0.011). There were no pressure differences between the locations for the i-gel.