The study aim was to establish by systematic review the prevalence of asymptomatic Chlamydia trachomatis infection of the lower female genital tract in Europe and also to assess the extent and effect of screening. The search process was wide ranging, using the electronic databases Medline, Embase and Aidsline and the Internet using the search engines Netscape and Euro-ferret. Studies published in any language during 1980-2000 were included if they unambiguously reported prevalence of C. trachomatis infection in asymptomatic women, and were assessed qualitatively. From >300 papers which quantified C. trachomatis urogenital infection, only 14 studies met the inclusion criteria: four from the UK, two from Sweden, two from The Netherlands, and one each from Bulgaria, France, Finland, Hungary, Italy and Spain. In only one study had screening taken place. The prevalence of C. trachomatis in unscreened asymptomatic women in Europe ranges from 1.7 to 17% depending upon the setting, context and country. The mode was -6% for women seeking contraception, and 4% for women having cervical smears. In conclusion, this review confirms high prevalence rates of C. trachomatis infection among asymptomatic women in many European settings.