Headaches are relatively common, often leading to impaired function and decreased quality of life. Physiotherapists and other manual therapists treat patients with headaches when musculoskeletal dysfunction is the likely source or a significant contributing factor. The aim of this study was to develop a specific disability measure for use in a population of patients presenting for physiotherapy treatment of headache. Patients (N=111) presenting to private physiotherapy practices in Victoria, Australia, for treatment of headaches completed a pre-existing, 16-item, headache disability questionnaire. Item responses were analysed separately to identify floor and ceiling effects and response rates, and by multivariate techniques to determine internal consistency and to identify unduly influential variables and underlying dimensions. Seven items from the original questionnaire were deleted due to significant floor effects, having low item-total correlations or after being judged unduly influential variables. The remaining nine items addressed the domains of pain severity, prevention of activity and reduction in ability to perform activities. The results of this study have led to the development of a valid and internally consistent questionnaire for measurement of the impact of headaches on patients receiving physiotherapy treatment. Further research is underway to examine the responsiveness and test-retest reliability of the questionnaire.