OBJECTIVE: To present results from the United States Cluster Headache Survey concerning the use of inhaled oxygen as acute treatment for cluster headache (CH). BACKGROUND: Several small clinic and community-based investigations have indicated that more than 50% of CH patients have never used oxygen for the treatment of their headaches. This statistic is alarming and the reasons why they have not tried oxygen have not been determined. METHODS: The United States Cluster Headache Survey is the largest study ever completed looking at CH sufferers living in the United States. The total survey consisted of 187 multiple choice questions, 84 questions dealt with oxygen use, efficacy and economics. The survey was placed on a website from October to December 2008. RESULTS: A total of 1134 individuals completed the survey (816 male, 318 female). Among them 868 patients had episodic CH while 266 had chronic CH. Ninety-three percent of survey responders were aware of oxygen as a CH therapy; however, 34% had never tried oxygen. Forty-four percent of patients had to suggest oxygen to their physicians to get prescribed. Twelve percent of physicians refused to prescribe oxygen. Fifty percent using oxygen never received training on proper use. Forty-five percent had to find their own source for oxygen. On prescriptions only 45% specified flow rate, 50% stated CH as diagnosis and 28% indicated mask type. Seventy percent of the surveyed population felt oxygen was effective but only 25% was presently using oxygen. Potential reasons for this finding include: oxygen is slow to onset; prescribed oxygen flow rates are too low for efficacy and most CH patients need to raise flow rates during attacks to achieve response. The efficacy of oxygen does not vary by the age of the patient, gender, the number of CH attacks per day, and smoking history. Episodic CH responds better and faster to inhaled oxygen than chronic CH. Oxygen plus a triptan may be more efficacious and faster at aborting a CH than a triptan alone. Sixteen percent of CH patients state that oxygen is unaffordable while 12% are getting welder grade oxygen because of costs of medical grade oxygen, and this form of oxygen could be potentially dangerous to the individual user. CONCLUSIONS: Oxygen is underutilized by CH patients living in the United States. Current recommended oxygen treatment regime is not meeting the needs of many CH patients. Prescribed oxygen flow rates are too low for efficacy. Oxygen can be expensive and very difficult to obtain. Physicians need to be better educated on the use of inhaled oxygen for CH.