To present results from the United States (US) Cluster Headache Survey including data on cluster headache demographics, clinical characteristics, suicidality, diagnostic delay, triggers, and personal burden. There are few large-scale studies looking at cluster headache patients and none from the USA. This manuscript will present data from The US Cluster Headache Survey, the largest survey ever completed of cluster headache patients living in the USA. The total survey was composed of 187 multiple-choice questions that dealt with issues related to cluster headache including demographics, clinical characteristics, comorbid medical conditions, family history, triggers, smoking history, and personal burden. The survey was placed on a Web site from October through December 2008. A total of 1134 individuals completed the survey (816 male, 318 female). Some key highlights from the survey include the following: (1) diagnostic delay: there remains a significant diagnostic delay for cluster headache patients on average 5+ years with only 21% receiving a correct diagnosis at time of initial presentation. (2) Suicidality: suicidal ideations are substantial, occurring in 55%. (3) Eye color: the predominant eye color in cluster headache patients is brown and blue, not hazel as suggested in previous descriptions. (4) Laterality: cluster headache has a right-sided predominance. (5) Attack profile: in US cluster headache sufferers, most attacks occur between early evening and early morning hours with peak time of headache onset between midnight and 3 am; the circadian periodicity for cluster headache is present but is not as predominant in the population as previously thought. (6) Triggers: beer is the most common type of alcohol trigger in US cluster headache patients; noted migraine triggers such as weather changes and smells are also very common cluster headache triggers. (7) Medical comorbidities: peptic ulcer disease does not have a high prevalence in US cluster headache patients as suggested by previous literature; cluster headache is associated with a low prevalence of cardiac disease as well as cerebrovascular disease even though the majority of patients are chronic heavy smokers. In US cluster headache sufferers, there appears to be comorbidity with restless leg syndrome, and this has not been demonstrated in non-US cluster headache populations. (8) Personal burden: cluster headache is disabling to the individual as almost 20% of cluster headache patients have lost a job secondary to cluster headache, while another 8% are out of work or on disability secondary to their headaches. Some findings from the US Cluster Headache Survey expound on what is currently known about cluster headache, while some of the results contradict what has been previously written, while other information is completely new about this fascinating headache disorder. © 2011 American Headache Society.