Objective: To assess the costs of headache-related absenteeism of community-dwelling migraineurs, and to compare the amount of absenteeism between migraineurs aged 18 and older and age, sex, and occupation-matched nonheadache-prone subjects. Design: Follow-up over a 3-mouth period. Samples: 385 migraineurs and 313 nonheadache subjects representative of the setting. Methods: Every day, the participants recorded the presence of headache, if any, and the work situation (unemployment, holiday, weekend, medical reason, nonmedical reason). Sickness-related absenteeism was the number of workdays missed or interrupted for medical reasons. Headache-related absenteeism was the sickness-related absenteeism during workdays with headaches. The annual headache-related absenteeism costs in France were extrapolated from these data in accordance with the mean income per occupational category. The incremental absenteeism and related costs were the difference between the two samples. Results: Of working migraineurs, 20% had at least one period of absenteeism. During the 3 months, they missed or interrupted on average 1.4 days for medical reasons, 0.25 of which for headaches. Sickness-related absenteeism was statistically higher in migraineurs than in nonheadache-prone subjects. This difference was due to a higher absenteeism for comorbidity reasons, not for headache reasons, representing 20%, of all sickness-related absenteeism. Migraineurs avoided sick leave for headache reasons. As an incremental total, 1.68 days or approximately 0.7% of the annual number of working days are lost on average per individual with migraine. The annual incremental headache-related absenteeism cost was 5.22 billions, i.e. 1,551 FF(US$240) per migraineur.