Chlamydia trachomatis is the most common bacterial cause of sexually transmitted disease in the developed countries. The most important implications of genital chlamydia infections involve the reproductive health sequalae of upper genital tract infections in women: pelvic inflammatory disease, ectopic pregnancy, and infertility, infection by this organism is insidious, symptoms are absent or minor among most infected women and many man. This large group of asymptomatic and infectious persons sustains transmission within a community. This review discusses the epidemiology, of sexually transmitted chlamydial infections, the spectrum of clinical manifestations and their sequelae, the laboratory diagnosis of genital chlamydiasis, antibiotic treatment and prevention.