Amplified DNA technology such as the polymerase chain reaction (PCR) and ligase chain reaction (LCR) are new techniques for the diagnosis of genital chlamydial infections in both men and women. These tests are highly sensitive and specific in detecting chlamydial genes in different specimen types such as genital samples as well as in non-invasive specimens such as urine and vulval smears. Due to the advantage of a high reliability of these techniques even when they are performed on non-invasive specimen types, amplification tests allow chlamydial diagnosis for screening especially high risk persons as the basis of chlamydia control programs.