Headache is the most frequent neurological symptom and commonest manifestation of pain in childhood. Measuring the impact of headache in terms of health status, functioning and quality of life can inform the prioritization of competing resource claims, screen for unmet need, improve communication between patient and physician and monitor response to treatment. We undertook a critical review of the literature measuring the impact of headache in children and identified 33 papers that contained relevant information. Findings reflected a wide range of settings, age groups, methodologies and outcome measures. Considerable methodological limitations affected all studies, including inadequate description of study design, methodology and data analysis. Nevertheless, although we found the existing literature to be of inconsistent quality, the impact of headache in children and adolescents is substantial. Rigorous studies are required to quantify this burden using measures that are valid and reliable and whose development has been informed by both theoretical and practical perspectives.