Clinical and laboratory studies were made in 2259 persons by using serological assays, including cultural and bacterioscopic assays in 1824 and 363 persons, respectively, in order to indicate Trichomonas infection among men, women, and 2-15-year-old children who had chronic inflammation of the urogenital system, as well as among children aged 2 months to 16 years who had a severe somatic disease. Parasitic cenoses of the urogenital tract were studied in women with trichomoniasis and reproductive dysfunction. Trichomonas invasion is an etiological factor of inflammatory small pelvic diseases, chronic prostatitis, reproductive dysfunction in males and females. Furthermore, trichomoniasis is an essential factor, that predisposes to recurrent viral infections: genital herpes and pointed condyloma, and substantially increases the risk of birth of babies with clinical manifestations of intrauterine infection. According to the studies, a laboratory diagnosis of trichomoniasis should be made by cultural assay due to the low sensitivity of bacterioscopy by sampling a biological material from females in the periovulatory period that corresponds to the hyperestrogenicity, which substantially increases the number of isolated cultures and characterizes the depth of integration of metabolic processes of a parasite and its host.