Objectives: This study aimed to determine the prevalence of genital and sexually transmitted infections and its related factors in married women in Iran. Methods: We conducted a cross-sectional study of 4 274 married women living in urban and rural areas of the Zanjan province from 2012 to 2013. We used stratified cluster sampling to select the participants. Data collection included demographic characteristics, reproductive status, and cervical cytology results. Results: The prevalence of lower genital infections and sexually transmitted infections were 20.1% and 7.4%, respectively. The most common vaginal infection was bacterial vaginosis with a prevalence of 8.5%, and the most common sexually transmitted infection was Trichomonas vaginalis (1.4%). The use of the intrauterine device (IUD) as a contraceptive, living in an urban area, and experiencing vaginal discharge were significantly related to genital tract and sexually transmitted infections. Conclusions: There was a high prevalence of genital infection among women living in Zanjab. Screening and treatment of genital infection are necessary to prevent adverse consequences in women who use an IUD or live in urban areas.