Pelvic inflammatory disease (PID) is the most important complication present in the female lower genital tract, causing major medical, social and economic problems. Although PID can be caused by multiple micro-organisms, it results most frequently from the ascent of sexually transmitted Chlamydia.trachomatis or Neisseria gonorrhoeae infections from the cervix to the upper genital tract. The importance of cervical chlamydial infection in the pathogenesis of PID is well recognized. Recent data from many developed countries have shown a striking decrease in the incidence of gonococcal infections, while the rates of chlamydial infections remain high in most countries. Complications of PID are common and usually irreversible. Emerging evidence suggests that universal or selected screening of defined populations for cervical chlamydial infection leads to a dramatic reduction in the incidence of PID. Recent technological advances should further enhance efforts to prevent chlamydial infection and PID. Gene amplification-based diagnostic tests, screening by testing first-void urine, and single dose antimicrobial therapy greatly facilitate chlamydia control programmes. Thus, screening for chlamydia is the key approach in the secondary prevention of PID. The obvious challenge is to make screening for chlamydia the standard for health care for young, sexually active individuals. Since PID is the most important consequence of sexually transmitted bacterial infections, it is also imperative to develop better treatments to prevent the long-term sequelae of this disease. The development and implementation of new and effective intervention programmes for prevention and control of PID is one of the major challenges for the year 2000 and beyond. Keywords: C.trachomatis/Neisseria gonorrhoeae/pelvic inflammatory disease