The relationships between migraine and A-V Malformations is a subject of controversy and the arguments are mainly based on case reports and retrospective data. To clarify this subject a structured inquiry and classification of headaches in large samples of patients with intracranial vascular malformations (IVM) is essential. The authors studied the prevalence of headaches in 51 patients with IVM admitted to our Department, between 1984 and 1992. The methods used were a review of medical records followed by a self-administered headache questionnaire and clinical interview using the IHS criteria for the diagnostic classification of headaches. The relative frequency of the different types of headaches was calculated and compared with the general population data. A correlative study of the headache characteristics with the type and location of the IVM was made. A high prevalence (47%) of migraine type headaches and a strong positive correlation (88.8%) between the site of AVM and side of the pain was found. This is highly suggestive but not conclusive of a pathophysiologic relationship between these entities. The conclusion drawn is that a prospective study of headaches by questionnaire or semi-structured clinical interview in patients with IVM is essential to discover the effective prevalence and characteristics of headaches associated with IVM and their relationships.