Primary chronic headache can affect a patient's health-related quality of life (HQL). The Medical Outcomes Study Short Form (SF-36) questionnaire has been used to address this issue. We compare the impact of headache on the HQL of patients with migraine and chronic daily headache (CDH) using the SF-36 instrument. We analyzed a group of 115 consecutive patients; 62 migraine patients and 53 CDH patients completed the questionnaire. Patterns of disability were similar between the two groups, but CDH was marked by a lower level of health scales. Patients with CDH had a significantly worse pain score in physical functioning, role functioning (physical), bodily pain, general health perceptions, and mental health than patients with migraine headache. Our results in the migraine group were similar to findings in other publications, with the lowest scores in role functioning (physical) and bodily pain. There is no previous experience in CDH patients, but the present data suggest that the SF-36 questionnaire is valuable in determining the differences in functional status among headache types. These data suggest that the SF-36 is a reliable and valid measure of the HQL of patients with CDH, and may indeed prove to be valuable in studying the efficacy of therapeutic agents for this type of headache.