The study analyzes the prevalence of cardiovascular risk factors in 1343 patients with severe headache (399 men and 944 women), aged 15 to 64 years; analyses were controlled for sex, age, and type and frequency of headache. Prevalence of various forms of headache was different between men and women. Age and days per year with headache were significantly different among various forms of headache. For men and women with headache, age directly related to prevalence of hypertension, hypercholesterolemia, and obesity. Due to low prevalence, analyses by age were not done for diabetes mellitus. For cigarette smoking, prevalence was not related to age in men, but was inversely related to age in women. With control for age, prevalence of cardiovascular risk factors was not significantly different among patients with different forms of headache, except for cluster headache. Among men with cluster headache, prevalence was high for cigarette smoking, but low for hypercholesterolemia. With control for age, days per year with headache did not relate to prevalence of cardiovascular risk factors except for cigarette smoking in men. Compared to data for a population sample used as control, patients with headache had higher prevalence of hypertension in both sexes, independent of age (odds ratio 1.51, 95% confidence interval 1.28 to 1.80); the difference between patients with headache and the control population was lower with increasing age. The high prevalence of hypertension among patients with headache was not due to overweight. The data indicate that headache is significantly associated with hypertension, but not with other cardiovascular risk factors.