Chlamydia trachomatis is the most common sexually transmitted disease in the Netherlands. Acute chlamydia infections can be detected accurately by sensitive laboratory tests. However, in women, up to 70% ofchlamydia infections are asymptomatic and remain unnoticed and untreated. It is assumed that about lo% of all cervical infections ascend to the upper genital tract, where they can cause salpingitis, which may lead to tubal pathology. Following a chlamydia infection of the upper genital tract anti-chlamydia IgG antibodies are formed that may persist for a long time in serum. After it was shown that IgG positive women had tubal pathology more often than IgG negative women, the chlarnydia IgG antibody test (CAT) was introduced as a cheap, simple screening test to assess the risk oftubal pathology. undergo an expensive, invasive procedure i.e. a laparoscopy. The positive predictive value ofthe CAT is 58%, and as a consequence there will be many false positive test results. In the future, the positive predictive value of the CAT may be improved by adding markers of persistent infections. The negative predictive value of the CAT is 92%, from which can be concluded that the CAT is a good test to rule out tubal pathology.