A patient interface structure for delivery of respiratory therapy to a patient includes a front plate configured to conform to the shape of the patient's face; a mouth cushion defining a breathing chamber and provided to the front plate and configured to seal around the patient's mouth; and a nasal cushion configured to seal the patient's nasal airways. The nasal cushion is supported by the mouth cushion, does not contact a bridge of the patient's nose in use, and extends at least partially into the breathing chamber. A patient interface system includes a patient interface structure and a patient interface structure positioning system configured to position, stabilize and secure the patient interface structure in sealing engagement with the patient's face.