In order to determine the prevalence of sexually transmitted infections (STI) in recluse women of Chorrillos Penitentiary I in the city of Lima, Peru, a cross-sectional study was performed, including a simple random sample of women between ages 18 and 54, from whom 180 serum samples and 168 samples of cervical and vaginal discharge were analyzed. The most prevalent etiologic agents identified from cervical and vaginal discharge samples were Chlamydia trachomatis in 42.3%, Gardnerella vaginalis in 24.4% and Trichomonas vaginalis in 10.1% and for serum samples the most prevalent were syphilis and HIV, both in 2.2%. We conclude that there is a high prevalence of sexually transmitted infections in recluse women of Chorrillos Penitentiary I in the city of Lima, Peru. There should be routine screenings established for diagnosis and treatment of STIs within the prison system and this population should be included in the sexual and reproductive health programs.