During the last decade researchers have begun to employ standardised methodologies to investigate the global impact of primary headaches. Disease-specific instruments have been developed to measure headache-related disability. The MIDAS Questionnaire, which is the most extensively studied of these instruments, was designed to assess the overall impact of headaches over the 3 months before compilation. The MIDAS Questionnaire is an optimal tool to assess headache-related disability in adults in relation to patients' daily activities. Primary headaches are a recurrent problem for children and adolescents. Forty percent of children have experienced headaches by the age of 7 years increasing to 75% by the age of 15. In a recent report we determined the suitability of the MIDAS Questionnaire in its original form for assessing disability in children and adolescents suffering from different kinds of headache. This was the first step of a line of research aimed to develop a new MIDAS Questionnaire adapted for young patients. In this second study the aims were: (1) to produce a new version of the MIDAS Questionnaire specific for young patients suffering from different forms of headache; (2) to assess the reliability of this new instrument; (3) to assess its sensitivity to treatment intervention.