Cerebral magnetic resonance imaging was performed on 63 patients with chronic primary headache (28 with migraine with and without aura, 35 with tension-type headache). Fifty-four headache-free individuals of the same age range were used as controls. The headache sufferers showed an incidence of focal white matter abnormalities on T2-weighted magnetic resonance imaging significantly higher than the age-matched control group (33.3% vs 7.4%). The incidence of white matter abnormalities did not correlate with age (except for patients older than 60 years), sex, headache history, headache status, or ergotamine consumption. Migraine (with and without aura) and tension-type headache patients had similar prevalence of white matter abnormalities (32.1% vs 34.3%). The lesions were predominantly distributed in the frontal region, independent of the side of usual aura or headache. Our findings indicate that both migraine and tension-type headache may be associated with early pathologic changes in the brain and may share, at least in part, common pathogenic pathways.