Pelvic inflammatory disease (PID) is caused by infection ascending from the cervix. It can affect the uterus, fallopian tubes, ovaries, and peritoneum. Important sequelae include infertility, ectopic pregnancy and tubo-ovarian abscess. PID is associated with sexually transmitted infections. These are more prevalent in younger women. A diagnosis of PID should be considered in any sexually active woman with recent onset pelvic pain associated with tenderness on bimanual examination where other differentials have been excluded. Delay in commencing treatment for PID has been shown to increase the risk of long-term complications.