Nine hypoxemic patients with COLD, whose hypoxemia is aggravated by minimal exercise, volunteered for this study. Each subject underwent two treadmill exercise trials at two oxygen delivery settings, each on the DODS and SF delivery systems for a total of four exercise trials. We measured SaO2 via ear oximetry and recorded oxygen usage per minute. We compared the oxygen usage required for the two techniques to achieve an SaO2 of 90 percent. The results indicate that the mean oxygen requirement using the DODS to achieve an SaO2 of 90 percent was 211.4 ml/min as compared to SF delivery which required 1,610.9 ml/min. This implies an oxygen savings advantage of the DODS over SF of 7:1. The fact that the DODS oxygen savings extends to exercise conditions lends support to its use in portable oxygen therapy. Widespread use of this and other oxygen savings techniques could result in significant cost savings while maintaining the desired benefits of supplemental oxygen administration.