Changes in the male-to-female (M/F) ratio of cluster headache (CH) over the years were investigated through a comparative analysis of the distribution of the disease by sex and decade of onset in 482 patients (374M and 108F). Variations over the last few decades were also investigated in the employment rate, level of school education, smoking habit, and coffee and alcohol intake of the population living in the same area as the CH patients. The M/F ratio has fallen from 6.2:1 for patients with CH onset before 1960, to 5.6:1, 4.3:1, 3.0:1, and 2.1:1 for patients with CH onset in the 1960s, 1970s, 1980s, and 1990s, respectively. Correspondingly, in those same decades, the M/F ratio has fallen from 2.6:1 to 2.4:1, 2.2:1, and 1.7:1, respectively, for the employment rate, and from 8.6:1 to 7.8:1, 3.3:1, 2.5:1, and 1.9:1 for the smoking habit. Such a close correlation suggests that the significant changes that have occurred over the last few decades in the lifestyle of both sexes--and particularly that of women--may have played a major role in altering the gender ratio of CH.