Abstract: A mask for relative analgesia and anaesthesia is moulded from polymeric foam and fits over the nose of the patient, with lateral ports for inlet and outlet of gases. The periphery of the mask has a lower region which bears upon the base of the upper lip, an upper region which contacts the nasal bones, and lateral regions which contact the nasal processes of the maxilla and the maxilla itself and meeet the lower region at the points where the base of the upper lip meets the naso-labial grooves. Certain parts of the face-contacting surfaces are inwardly chamfered.