A harness for securely positioning a nasal cannula on the face of a person for orally administering oxygen and other gases is described. A flexible chin strap adapted for placement around the chin of the person may be attached to adjustable, flexible straps effective for draping around the ears of the person, which are in turn attached to a central, cannula attachment portion disposed between the cannula and the face of the person. The gas delivery tubes of the cannula are also disposed behind the ears, essentially following the path of the flexible straps of the harness. Once placed on a person, the harness holds the nasal cannula such that the nasal prongs may disposed facing toward the mouth opening in the vicinity of the lower lip thereof, and may deliver gases to a mouth-breathing individual. Another embodiment of the harness may be utilized to position a nasal cannula for nasal administration of gas.