Two hundred and forty-nine patients with cluster headache have been studied, 215 male and 34 female (ratio 6.3:1). Twenty-five of the 26 fertile female cluster patients stated that their headaches had no relation to menstrual periods. Eight had had 13 pregnancies since the onset of cluster headache. Six of them experienced remission of their headache during pregnancy. Four women with cluster headache had a history of infertility or premature menopause. Parity rate was low in patients who contracted cluster headache as nulliparae; it was lower than in those who contracted the disease after earlier pregnancy or post menopause, and also significantly lower than in 99 consecutive women with migraine. Significant differences were also found when the numbers of childbirths in the cluster patients were compared with total fertility rates up to successive ages for birth cohorts in the general population of Swedish women.