C. trachomatis is considered the most common sexually transmitted bacterial pathogen. At least 3 million new cases occur each year in the United States, with more than 80 million worldwide. It is a major cause of cervicitis, urethritis, endometritis, and pelvic inflammatory disease in women. If transmitted to infants during birth, Chlamydia can cause conjunctivitis and pneumonia. In men, complications of chlamydia infections include urethritis and epididymitis. Approximately 70% of women with endocervical infections and up to 50% of men with urethral infections are asymptomatic, which makes diagnosis extremely important.