The objective of this paper is to provide a review on available data to date on the epidemiology of GAD in Europe, and to highlight areas for future research. MEDLINE searches were performed and supplemented by consultations with experts across Europe to identify non-published reports. Despite variations in the design of studies, available data suggest that (a) about 2% of the adult population in the community is affected (12-month prevalence), (b) GAD is one of the most frequent (up to 10%) of all mental disorders seen in primary care, (c) GAD is a highly impairing condition often comorbid with other mental disorders, (d) GAD patients are high utilizers of healthcare resources, and (e) despite the high prevalence of GAD in primary care, its recognition in general practice is relatively low. Marked data deficits are: lack of data from eastern European countries, lack of information about the natural course of GAD in unselected samples, the vulnerability and risk factors involved in the aetiology of GAD and lack of data about adequate and inappropriate treatments in GAD patients as well as the associated and societal costs of GAD.