The multiple etiology of non-gonorrhoic urethritis has been extensively investigated in the last few years. It has thus become possible to diagnose the separate forms and consequently treat them with a greater degree of accuracy and specificity. For exact diagnosis multiple and time consuming examinations are often necessary. Sometimes this can only be done in highly specialized laboratories. Among the agents triggering such an infection Chlamydia (30.9% of the cases of non-gonorrhoic urethritis), as well as mycoplasma, ureaplasma, anaerobic bacteria and herpes simplex viruses have gained particular significance. Whereas these infections very rarely lead to complications by ascension in men they can result in unpleasant and severe disease in women (salpingitis, infertility, newborn infection).