Cluster headache (CH) is a rare underdiagnosed primary headache disorder with very severe unilateral pain and autonomic symptoms. Clinical characteristics of Korean patients with CH have not yet been reported. We analyzed the clinical features of CH patients from 11 university hospitals in Korea. Among a total of 200 patients with CH, only 1 patient had chronic CH. The average age of CH patients was 38.1 +/- 8.9 years (range 19-60 years) and the average age of onset was 30.7 +/- 10.3 years (range 10-57 years). The male-to-female ratio was 7: 1 (2.9: 1 among teen-onset and 11.7: 1 among twenties-onset). Pain was very severe at 9.3 +/- 1.0 on the visual analogue scale. The average duration of each attack was 100.6 +/- 55.6 minutes and a bout of CH lasted 6.5 +/- 4.5 weeks. Autonomic symptoms were present in 93.5% and restlessness or agitation was present in 43.5% of patients. Patients suffered 3.0 +/- 3.5 (range 1-25) bouts over 7.3 +/- 6.7 (range 1-30) years. Diurnal periodicity and season propensity were present in 68.5% and 44.0% of patients, respectively. There were no sex differences in associated symptoms or diurnal and seasonal periodicity. Korean CH patients had a high male-to-female ratio, relatively short bout duration, and low proportion of chronic CH, unlike CH patients in Western countries.