A sealing cushion (16) for a respiratory mask assembly (10) has a patient interface portion (18) having a resiliently deformable membrane (24) for engagement with a patient's face, and an aperture (26) formed therein for receiving a nasal and/or mouth region of a patient's face. An inner surface of the membrane has a plurality of projections (32, 34, 36, 38, 40). The projections (32, 34, 36, 38, 40) are arranged such that each projection (32, 34, 36, 38, 40) is engageable with an adjacent projection (32, 34, 36, 38, 40) on deformation of the membrane (24) during engagement of the membrane (24) with the patient's face, in use, thereby providing the membrane (24) with an increased resistance to deformation in a deformed configuration.
