Pelvic inflammatory disease (PID) is a common infection in women of reproductive age. PID is actually a spectrum of disease, beginning with cervicitis and progressing to endometritis and eventually salpingitis. Sequelae include ectopic pregnancy, infertility, chronic pelvic pain, hydrosalpinx, and tubo-ovarian abscess. Neisseria gonorrhoeae and Chlamydia trachomatis are the primary causes of PID. Chlamydial infection may be asymptomatic, and the resulting salpingitis is often referred to as "silent PID." Polymicrobial infection with other organisms (eg, anaerobes, facultative aerobes) may be initiated by gonorrhea, chlamydial infection, or both. Early recognition of infection, prompt institution of appropriate antibiotic therapy, and proper follow-up are important to prevent the sequelae of PID. Patient education is essential to reduce the incidence of PID.