We assessed functional disability and health-related quality of life (HRQOL) in Italian patients suffering from chronic migraine and medication overuse (150 subjects) or chronic cluster headache (22 subjects). We used the validated Italian versions of the Migraine Disability Assessment Score (MIDAS) and of the Short Form 36 (SF-36). Patients with both conditions were characterised by significantly lower scores on most SF-36 scales than Italian normative data (Student's t test with Bonferroni correction). MIDAS scores revealed that patients had severe limitations in their ability to function, with high proportions forced to stop work and non-work activities, or experiencing significantly reduced productivity in all activity domains. These findings show that primary chronic headaches have a marked negative influence on patients' lives, compromising their sense of well being and their ability to function in different roles. We also found that MIDAS and SF-36 were sensitive to clinical changes in a group of 84 patients with chronic migraine and medication overuse who completed the both questionnaires before and after treatment.