This article reviews the two intrauterine devices (IUDs) available in the United States: the TCu380A, marketed as ParaGard (Duramed Pharmaceuticals, Inc. Pomona, NY), and the levonorgestrel-releasing intrauterine system (LNG-IUS), marketed as Mirena (Bayer HealthCare Pharmaceuticals, Inc., Wayne, NJ). The properties of the two devices are detailed, as well as noncontraceptive indications and appropriate candidates for use. Studies consistently demonstrate that the devices are safe, effective, and provide cost savings when compared with other reversible methods. The TCu380A may be used as postcoital contraception with close to 100% effectiveness. Menstrual blood loss is likely to increase with the TCu380A and decrease with the LNG-IUS. Reduction in menstrual blood loss and endometrial suppression make the LNG-IUS an Increasingly Popular treatment for menorrhagia, endometriosis, adenomyosis, and as an adjunct to estrogen therapy. IUDs may be inserted immediately after a first- or second-trimester abortion, immediately postpartum, and >= 4 weeks postpartum. Candidacy for IUDs has expanded, and includes nulliparous women, adolescents, and women with immunocompromised conditions including HIV.