The role of parasites and fungi in secondary infertility-Serbia [No authors listed] INTRODUCTION: Parasite-host relationships can cause diminished or absent ability to conceive, ectopic pregnancy or pregnancy with undesired course. LITERATURE REVIEW: There are reports that some protozoa, helminths and fungi may impair women's reproductive capacity, causing deformities of genital tract, so that conception is impossible, or, if it does occur, normal implantation and development of placenta are impossible. Schistosoma haematobium may cause vulvar papule, swelling, tumors, irregular vaginal hemorrhage, tubular infertility and ectopic pregnancies. Patients with cirrhosis caused by schistosomas have gonadal dysfunction and schistosomiasis itself can lead to tubular infertility. Some authors found microfilaria of Mansonella perstans in follicular aspirates in patients with tubular adhesions. Chronic Entamoeba histolytica infection can cause pelvic pain and dyspareunia in some patients. Although Trichomonas vaginalis is a common cause of tubal inflammation, this protozoa affects semen quality and leads to secondary infertility. Soluble parasite extract of T. vaginalis can lead to impaired motility of 50% spermatozoa in vitro and affects semen quality by increased viscosity and amount of debris, or damage spermatozoid membrane. In enterobiosis, presence of adult worms and eggs in fallopian tube, can be followed by chronic salpingitis and tubal occlusion. Also in ascariosis, presence of adult forms and eggs can lead to acute colpitis. chronic endometritis, salpingitis or ovarian abscess. The consequence of fungal infections, such as colpitis and endometritis, caused by Candida albicans, may be infertility. Also, according to some reports, C. albicans leads to decreased spermatozoan motility. CONCLUSION: Hence parasites and fungi can cause infertility, we recommend examination of both partners in treatment of infertility.