Pelvic inflammatory disease (PID) is an infection of the upper genital tract occurring predominantly in sexually active young women. Chlamydia trachomatis and Neisseria gonorrhoeae are common causes; however, other cervical, enteric, bacterial vaginosis-associated, and respiratory pathogens, including Mycobacterium tuberculosis, may be involved. PID can be acute, chronic, or subclinical and is often underdiagnosed. Untreated PID can lead to chronic pelvic pain, infertility, ectopic pregnancy, and intra-abdominal infections. The diagnosis is made primarily on clinical suspicion, and empiric treatment is recommended in sexually active young women or women at risk for sexually transmitted infections who have unexplained lower abdominal or pelvic pain and cervical motion, uterine, or adnexal tenderness on examination. Mild to moderate disease can be treated in an outpatient setting with a single intramuscular injection of a recommended cephalosporin followed by oral doxycycline for 14 days. Additionally, metronidazole is recommended for 14 days in the setting of bacterial vaginosis, trichomoniasis, or recent uterine instrumentation. Hospitalization for parenteral antibiotics is recommended in patients who are pregnant or severely ill, in whom outpatient treatment has failed, those with tubo-ovarian abscess, or if surgical emergencies cannot be excluded. Treatment does not change in patients with intrauterine devices or those with HIV. Sex partner treatment is recommended; expedited partner treatment is recommended where legal. Prevention of PID includes screening for C. trachomatis and N. gonorrhoeae in all women younger than 25 years and those who are at risk or pregnant, plus intensive behavioral counseling for all adolescents and adults at increased risk of sexually transmitted infections.