TNF and polycystic ovary syndrome: Methods: The research in the presented paper focuses on a group of women with PCOS (n = 490) of reproductive age (26–43 years), in whom the frequency of infections of the reproductive system caused by atypical pathogens, Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma spp., were analyzed, and then the immune system response was assessed in terms of the level of serum proinflammatory cytokines, IL-1β, IL-6 and TNF-α.