PrevalenceHeadache is one of the most common reported complaints in the general adult population and it accounts for between 1% and 3% of admissions to emergency departments (ED) [1,2]. Despite the fact that this symptom is very widespread and is a costly medical condition, the diagnosis of headache and its epidemiological impact in the ED has still not been completely considered. This is because most of the data collected in this field are obtained with retrospective studies. From this point of view it has been shown that the incidence of primary headache (PH) diagnosis is lower in the ED than in the general population [1][2][3][4][5][6][7][8][9].In a multicentre retrospective Italian study [3] done to evaluate the prevalence of primary headache in the ED, it accounted for 0.6% of all attendances. In an observational three-month pilot study, executed by our team in 2002, we found a prevalence of 1.2% of headache complaints in the ED (unpublished data).An unexpected aspect of the data obtained in our study was the equal prevalence of secondary (52%) and primary (48%) headache in this population.Out of PH, migraine headache is a common presenting complaint to the ED. The prevalence of migraine diagnosis at discharge from emergency is very variable, ranging from 15 to 32% [3,8,9]. The majority of patients were discharged with a diagnosis of cephalalgia or headache not otherwise specified (NOS) [3,8,9]. J Headache Pain (2005) Abstract Headache is one of the most common reported complaints in the general adult population and it accounts for between 1% and 3% of admissions to an Emergency Department (ED). The overwhelming majority of patients who present to an ED with acute primary headache (PH) have migraine and very few of them receive a specific diagnosis and then an appropriate treatment. This is due, in part, to a low likelihood of emergency physicians diagnosing the type of PH, in turn due to lack of knowledge of the IHS criteria, and also the clinical condition of the patients (pain, border type of headache, etc.) In agreement with the literature, another interesting aspect of data emerging from our experience is that few of the ED PH patients are referred to headache clinics for diagnosis and treatment, especially if they present with high levels of disability. This attitude promotes the high-cost phenomenon of repeater patients that have already been admitted to the ED for the same reason in the past. This is statistically important because it involves about 10% of the population with PH.6:287-289 DOI 10.1007/s10194-005-0210-1 Primary headache in Emergency Department: prevalence, clinical features and therapeutical approach