To systematically review the worldwide evidence on the prevalence of domestic violence against women, to evaluate the quality of studies, and to account for variation in prevalence between studies, using consistent definitions and explicit, rigorous methods. Systematic review of prevalence studies on domestic violence against women. Literature searches of 6 databases were undertaken for the period 1995 to 2006. Medline, Embase, Cinahl, ASSIA, ISI, and International Bibliography of the Social Sciences were searched, supplemented by hand searching of the reference lists from studies retrieved and specialized interdisciplinary journals on violence. A total of 134 studies in English on the prevalence of domestic violence against women, including women aged 18 to 65 years, but excluding women with specific disabilities or diseases, containing primary, empirical research data, were included in the systematic review. Studies were scored on eight pre-determined criteria and stratified according to the total quality score. The majority of the sudies were conducted in North America (41%), followed by Europe (20%). 56% of studies were population-based, and 17% were carried out either in primary or community health care settings. There was considerable heterogeneity both between and within geographical locations, health care settings, and study quality The prevalence of lifetime domestic violence varies from 1.9% in Washington, US, to 70% in Hispanic Latinas in Southeast US. Only 12% scored a maximum of 8 on our quality criteria, with 27% studies scored 7, and 17% scored 6. The mean lifetime prevalence of all types of violence was found to be highest in studies conducted in psychiatric and obstetric/gynecology clinics. Results of this review emphasize that violence against women has reached epidemic proportions in many societies. Accurate measurement of the prevalence of domestic violence remains problematic and further culturally sensitive research is required to develop more effective preventive policies and programs.