A study was conducted to determine the effect of oxygen inhalation by nasal cannula on oral temperatures. One hundred healthy adult subjects were randomly assigned to a control and to three experimental groups that received 2, 4, and 6 liters per minute of oxygen for 30 minutes. Oral temperatures were measured before and 30 minutes after oxygen treatment. The data analysis did not show any significant effect of the treatment. This study encourages review of the common empirical practice of changing temperature sites from the preferred oral to the less acceptable rectal or axillary sites in patients receiving oxygen inhalation treatments.